Tsukasa Kadoya

Tsukasa Kadoya (門矢 士) is a hypocritical and self-righteous traveler whose role as the The Destroyer of Worlds (世界の破壊者) is to observe the various Worlds of the Rider Multiverse and bring balance to them as Kamen Rider Decade (仮面ライダーディケイド).

In Kamen Rider Zi-O, Tsukasa returns as a series regular with a new belt. Observing the actions of Sougo Tokiwa, his current goal is to determine whether his world is required to be destroyed or not.

Discovering His Powers
Ten years before the start of the series, Tsukasa's parents died and he was left with the Kadoya family butler, Tsukikage, to raise his younger sister, Sayo. Because she was afraid to go outside, she discovered the ability to open up dimensional walls. Tsukasa took advantage of this and he discovered he could do it as well and used this ability to explore different worlds, while she stayed cooped up in her room.

In his teens, he was appointed Grand Leader of Dai-Shocker and accepted the position because as Sayo explained in the movie, he thought "it would be fun". After being given the Rider Booker and DecadeDriver, he set off to subjugate the Riders in all the different A.R. Worlds one year before the start of the series. The shock of traveling through the A.R. Worlds caused him to lose his memories and he wound up in an A.R. World where Natsumi Hikari lived with her Grandfather without any memories of his history, other than how to fight and that he was sure it was not 'his' World.

Becoming Decade
When Tsukasa is confronted by Natsumi over the photos he has taken, the two get separated by a dimensional barrier that sends Natsumi into an unstable pocket dimension where she flees for her life from various kaijin before finding the Decadriver from her dreams. While looking for her, Tsukasa encounters Wataru Kurenai, who calls him "Decade". Wataru tells him today is the day his world will end, and that he is needed to protect it.

After finding Natsumi, Tsukasa uses the Kamen Ride Cards to assume the forms of Kabuto, Faiz and Hibiki to deal with groups of Worm, Orphnoch and Makamou. Confused by both his actions and the cards' powers fading, Tsukasa takes Natsumi and returns to their world as it is being destroyed by the various monsters. When time suddenly freezes, Wataru appears, revealing the status of the worlds and assigning Tsukasa the task of traveling to the other worlds to stop the dimensional chaos inflicted on his own world by meeting the Riders of each of the other dimensions while the rest of the Main Riders freeze time in the meanwhile.

{{#tag:tabber| The Nine Worlds=

World of Kuuga
Starting in the World of Kuuga as a police officer, Tsukasa meets the world's Rider, Yusuke Onodera who battles the Gurongi and learns that that someone is disseminating rumors across the Worlds about him as the World Destroyer. After reconciling with Yusuke, the two stop the Gurongi N-Gamio-Zeda from taking over the world.

World of Kiva
At the World of Kiva as a violinist, Tsukasa encounters the young boy Wataru, helping the boy realize his role as King of the Fangire Race to maintain the peaceful coexistence of the human and Fangire races while defeating the Beetle Fangire: Wataru's father and the former King.

World of Ryuki
Then at the World of Ryuki, Tsukasa defends the framed Natsumi in a murder case and solves it with the aid of Shinji Tatsumi. The true villain, Kamata is revealed to have been an Undead all along and is taken by Narutaki to the World of Blade after his defeat.

World of Blade
Assuming the role of chief waiter under the BOARD Corporation while being promoted repeatedly, Tsukasa works with Kazuma Kendate to uncover the conspiracy between Kamata and BOARD's CEO, Kamen Rider Chalice, to take over the world through the Joker card which the latter used on himself. After he and Blade work together to defeat the Undead, Tsukasa takes his leave as Kazuma thanks him.

World of Faiz
In the World of Faiz as a student of the Smart Brain High School, Tsukasa crosses paths with a man he saw at the World of Blade who knows him, Daiki Kaito. Though Kaito warns him to stay out of his affairs, Tsukasa finds Faiz after confronting the Lucky Clover group, learning that he is Takumi Ogami as he attempts to keep his SB-555B Faiz Driver away from Kaito. Tsukasa later resolves the tension between Takumi and Yuri Tomoda over Takumi's identity, giving Takumi the will to continue protecting the school.

World of Agito
Arriving in the World of Agito as a postman, Tsukasa reads a discard letter meant for Shouichi Ashikawa, making it his goal to protect Ashikawa from the Unknown for the sake of Toko Yashiro, the writer of the letter. With Yusuke's help, Tsukasa succeeds in having Shouichi achieve the necessary state of mind needed to complete his evolution to Agito before reuniting him with Yashiro.

World of Den-O
Upon arriving in the World of Den-O, Tsukasa becomes Den-O under the possession of an Imagin, before forcing him into Yusuke's body. Here, he learns that some unknown force is changing the past as he is fought by the other Taros possessing Natsumi's body who believe Decade to be the source. Learning the Imagin possessing Yusuke is named Momotaros, Tsukasa finds him and helps him regain his physical form as they defeat the Alligator Imagin. Believing their adventures with Den-O to be over, only to learn the identity of the true culprits for Den-O World's time distortions, they prepare to travel to the World of Kabuto until the Swan Imagin Sieg comes into the Hikari Studio with a manuscript showing a battle at Onigashima. With Sieg's help, Tsukasa and company travel with the DenLiner crew back in time to fight the Oni Rider Brothers, Mimihiko and Kuchihiko, before returning to the present time in the World of Kabuto.

World of Kabuto
In a ZECTrooper role, after witnessing TheBee and Gattack's fight against a Worm, Tsukasa brings Arata to the Photo Studio where he finds a Salis Worm that had mimicked him. After the impostor is exposed, the Worm is killed by Kabuto when it attempted to kill a girl named Mayu whose brother was believed to have been killed by Kabuto. Although it seemed that TheBee's user, Sou Otogiri, is her brother, Tsukasa felt something was not right. After learning that Mayu herself is a Worm, both his meeting with Grandma and learning the full nature of the Kabuto Capture Plan allow him to get the full story. Arriving to Mayu's aid, Tsukasa helps Kabuto, Mayu's real brother Souji, in defeating Otogiri in his true identity, the Phylloxera Worm. After bringing Mayu back to her Grandma and giving Daiki a vial of pepper as a "treasure", Tsukasa begins the journey into the final world, the World of Hibiki.

World of Hibiki
In the World of Hibiki, Tsukasa meets and encounters an Oni in training named Asumu. From there, believed to be the Great Master of Ongekidō (音撃道) style, Tsukasa meets the three masters of the Ongekidō Styles before being pulled into a ploy by Daiki to rob the two Oni masters Ibuki and Zanki, worsening when they are attacked by the Makamou Gyuki until Akira and Todoroki drive the beast off. Supporting their intent to end the rivalry among their schools, Tsukasa convinces Ibuki and Zanki to pass the torch. Tsukasa later offers his aid to Asumu after he became the new Hibiki thanks to Daiki, whom he still acknowledged as a thief and nothing more.

The New Worlds=

World of Negatives
With the journey over, Tsukasa and the others of the Hikari Studio return to what appears to be Natsumi's world to find it back to normal as if it was not plagued by the monsters. Despite being in a perfect world that he has earned, according to Otoya Kurenai, it is revealed that it is only a parallel version of their own world where the monsters have taken over and killed all but a few humans.

After being tested by Otoya, Tsukasa gains the K-Touch after turning down Otoya's offer to live in a world of lies, using Decade's Complete Form to combat the Dark Riders. Tsukasa defeats Ryuga, Orga and Dark Kabuto with the finisher of Ryuki Survive, Faiz Blaster and Kabuto Hyper. Knowing that their journey is not really over, after Natsumi drops the next background the Hikari Studio group heads to the next world, Kaito's homeworld.

World of Diend
Arriving in the World of Diend, he finds himself in the role of a salary man selling products to the society until he encounters Shin and Haruka, Kamen Riders Lance and Larc, fighting a Darkroach.

He learns that Daiki is the lackey of the evil Fourteen who brainwashed the inhabitants of the World of Diend to believe that Kamen Riders are evil, having unknowingly given up his brother to Fourteen. He and Daiki team up to defeat Fourteen to free all those who have been brainwashed, leaving only Daiki's brother Junichi, Kamen Rider Glaive, who was not brainwashed but accepting of Fourteen's peaceful world. He teaches the two brothers that they have to protect each other, no matter what, before heading off to the next world, one which he has no knowledge of at all.

World of Shinkenger
In the guise of a with a strange card in hand, Tsukasa learns that his lack of knowledge is due to the world not having any Kamen Riders as he witnesses the  drive off the Nanashi. Curious about them, Tsukasa uses his guise to learn more about them and their world before fighting the Ayakashi Chinomanako who stole the Diendriver from Daiki. He realizes that the monster is the reason why he is in this world as Chinomanako escapes and becomes the world's first Kamen Rider. He attempts to fight the Chinomanako but is stopped by Narutaki saying that his actions will only bring doom to the world. After being given the advice to do the right thing by Hikoma Kusakabe, Decade later helps the Shinkengers with the card revealing to be the Rekka Daizantou which he uses to destroy Chinomanako alongside Shinken Red using the Blade Blade. As Tsukasa and Yusuke are welcomed home by Eijiro and Natsumi, assuring Tsukasa that the photo studio is his home no matter what, they enter a new A.R. World.

World of Black RX
Entering the World of BLACK RX, receiving another card and being mistaken as Joe the Haze when he changes clothes, Tsukasa is attacked by Schwarian and his Chap minions while meeting Kotaro Minami himself. Decade then finds out that Dai-Shocker is in this world planning to conquer it. Decade teams up with RX to help fend off the assault on this world. Eventually the Security Chief of Dai-Shocker, Apollo Geist drains Natsumi's life through his Perfector ending up in a hospital and Tsukasa desperate to revive her. Decade learns of Apollo Geist and the Perfector from Kaito and goes off to find him, but Kaito also has his agenda of retrieving the device. Decade, with assistance from RX, battles Geist but Guy leaves through a dimension wall. Tsukasa follows him in pursuit but ends up in Kamen Rider BLACK's World with no way out.

World of Black
BLACK attacks Decade after he mistakes him for RX's Kotaro Minami. Decade refuses to fight and Diend appears to stop BLACK with Femme's power. They retreat and Decade continues his search for Guy. As Ryuki he fights him and saves a child, gaining BLACK's trust in the process and teaming up with him. They come across Geist and the newly recruited Schwarian, although Guy escapes through a dimensional wall. BLACK uses "King Stone Flash" to help Tsukasa get back to RX's world through the wall. Decade re-encounters the RX Kotaro and finds Guy. His card is revealed to be a Kamen Rider BLACK card but Diend uses it instead and the two Kotaros transform and fight Geist and Schwarian. Decade is able to get the Perfector but Diend steals it and runs away. Decade then destroys Schwarian with Agito's powers while the two BLACKs force Geist into retreating.

At the hospital Kaito hands over the Perfector, saying that there are other treasures that he has already taken from this world and there are always more to get from other worlds. Kaito takes his leave telling Tsukasa to save his friend. Decade uses the Perfector to drain part of his life and implant it into Natsumi reviving her. Before leaving, Tsukasa tells Kotaro that Joe the Haze is helping his counterpart. But Kotaro is not saddened by it, knowing that Joe will be with him in spirit. The gang returns to the photo studio where the next world is waiting.

World of Amazon
When Tsukasa enters Amazon's world he immediately assumes the mantle of a baseball player and receives yet another card. He immediately sees that Dai-Shocker has taken over this world and is attacked by some of the monsters from different worlds. Amazon appears suddenly and helps Decade fight them but before a finishing blow could be done the people intervened convinced by Dai-Shocker that riders are destroyers forcing them to retreat.

They run into Kaito again where he explains his plan to steal Amazon's GiGi armlet's counterpart, the GaGa armlet which is unfortunately owned by the Ten-Faced Demon Llumu Qhimil, Dai-Shocker's designated ruler of the World of Amazon. Llumu sends out Masahiko Okamura to reveal the Rider's location by faking an attack by the Dai-Shocker foot soldiers and gaining their trust. Apollo Geist appears once more fighting Decade demanding his Perfector but Decade destroys it instead. The fight goes on until Masahiko steals the GiGi armlet after Dai-Shocker turns on him.

With Dai-Shocker now aware of where the Riders might go the gang goes to a nurse's office at Shocker School where Tsukasa finds a picture of Masahiko and his family before his father passed away. They are then driven off by Masahiko's older sister and the Dai-Shocker foot soldiers. They quickly come up with a plan to retrieve the GiGi armlet after Masahiko turned it over to them and was put up to be the first in the Humanity-to-Monster Project. He is saved by Tsukasa and Yusuke in disguise as foot soldiers and explains what happened. As they go out and retrieve the GiGi Armlet Amazon joins the fight against Llumu Qhimil, while Diend successfully obtains the GaGa Armlet during the battle. However this is short-lived as Tsukasa uses the armlet for himself through the use of his new card until giving it to Amazon who delivers the final blow to Llumu with Super Big Slice. Amazon is then adopted into Masahiko's family and the gang returns to the photo shop to find Diend sitting there and he proposes that he go with them.

World of Decade
The Hikari Family Studio ends up in a world which is discovered to be Tsukasa's home world, the World of Decade, where Tsukasa meets his sister Sayo Kadoya and starts a tournament to find the strongest Rider to save the world after hearing he must be the one to do so by Nobuhiko Tsukikage, Sayo's butler.

Tsukasa wins and it is revealed that he was the Great Leader of Dai-Shocker. But the victory is short lived as Nobuhiko is revealed to be Shadow Moon and Sayo as Priestess Bishium takes control of Yusuke through the Stone of Earth to attack Tsukasa as part of revenge for abandoning her, despite not knowing the truth. Tsukasa is left alone as even his friends abandoned him. He is later encountered by Joji Yuki a former scientist for Dai-Shocker that wanted payback by Tsukasa for doing said punishment to him. Later he realizes that Tsukasa is no longer affiliated with Dai-Shocker and fights Dai-Shocker as Riderman as Tsukasa moves away.

Tsukasa joins in the fight against Dai-Shocker starting with the fight against General Jark. He and all of the Kamen Riders from the Showa and Heisei Era fight Dai-Shocker destroying Ambassador Hell and Doctor Shinigami as Garagaranda and Ikadevil respectively. Later Decade fights the Bishium-controlled Kuuga Rising Ultimate but realizing he's talking with his sister, he convinces Sayo that Nobuhiko is only using her to further his goals. Sayo knowing the error of her ways destroys the Stone of Earth, freeing Yusuke. With the stone destroyed Shadow Moon fights Decade and Kuuga Rising Ultimate overpowering them until Double shows up and flings him to Dai-Shocker's castle. Tsukasa along with all of the other riders destroy Shadow Moon with the All Rider Kick. After Shadow Moon and the castle is destroyed, King Dark appears. Diend summons J and uses the Decade Final Form Ride to turn Decade into the Jumbo Decadriver and turns J into Decade Complete Jumbo Formation destroying King Dark. Tsukasa later makes amends with Sayo and leaves with the Hikari Studio.

The Rider War=

World of the Rider War
The Hikari Studio heads to the next world which will be the site where all the riders are supposed to be; "The Rider War World". It is the same place that Natsumi saw when she had her dream about the war. The Rider War World is Decade's undoing as he witnesses both Kamen Riders Blade and Kiva lead Rider armies against each other. Tsukasa and Yusuke try to keep both sides from killing each other and find that the Fangire Queen, Yuki, has married Guy who becomes Super Apollo Geist. With this new enemy Tsukasa destroys Yuki with Ryuki Survive's abilities and the rest of the Fangire and Undead armies with help from Kazuma Kendate and Wataru. Unfortunately Super Apollo Geist uses his powers to make the worlds merge with Kazuma and Garren disappearing and Geist kidnaps Natsumi. He is then confronted by Kazuma Kenzaki, the original Kamen Rider Blade. Decade finally finds out why the worlds are merging and it is because of Decade himself. Kenzaki tranforms and assumes King Form, Decade is quickly defeated. Decade returns to the photo studio injured and finds out that every picture he took in the other worlds are completely blank because they are nearly gone. Decade heads out to follow Kiva-la and is confronted by Hibiki and Kiva who fight him. The two Riders were talked into helping Kenzaki save their own worlds. Kuuga saves Decade while he deals with Geist.

Decade catches up to Geist who has brought back all the different monsters he fought in the different worlds. Decade is quickly overwhelmed by too many enemies but with Kuuga, Hibiki, Kiva, and Diend he manages to drive the creatures back. Decade immediately fights Geist who has become very powerful with his super mode. Diend hands Decade his Kamen Ride Card and with the power of Diend the two annihilate Geist. Decade is exhausted and collapses with Kiva and Hibiki finally fading away because their worlds no longer exist. Decade is taken to the place where it all started the place where he met the original Wataru. Wataru explains that Tsukasa messed up his job and says that he and the others will fight him as he transforms into Kiva. Decade is again transported to the War world where the original Riders appear and Kuuga becoming Ultimate Form to fight Decade due to Kiva-la. Diend aims his gun directly at Decade's head at point blank range. With that the Rider War begins.

Decade's Final Chapter and Teaming Up with Double
"The answer is simple. I am the destroyer of all. I have accepted that."

- His answer when Natsumi confronts him about him accepting what others used to gossip about him. In Decade: Final Chapter, despite being unwillingly the Destroyer of Worlds, Tsukasa accepted his role and turns into Violent Emotion Decade, destroying all Riders and began turning them into cards. He was assisted by Yuriko Misaki who reminded him of himself and could transform into Electro-Wave Human Tackle. He was later confronted by Natsumi who has become Kamen Rider Kiva-la to stop his rampage. Before Tsukasa died, after voluntarily letting her kill himself, he gave Natsumi the Kamen Ride Cards and told her that as long as people remember the Riders they would never disappear.

Natsumi and Kaito learnt from Wataru Kurenai of Decade's role as the destroyer and connector of worlds, as Tsukasa would destroy the Riders he would connect the other worlds preventing their collapse and does anything he was needed for as a hero or a villain to finish the Rider's story. He himself however had no story and with his task complete Decade was gone forever. Despite this, Natsumi found a way to revive him through the use of a picture and the A.R. Riders' memories, and Tsukasa was resurrected. Tsukasa and the gang along with other Riders fought against Super Shocker receiving more help from Kamen Rider Double whom he met in his summer movie. With Double's Final Form Ride and Final Attack Ride, he and Double destroyed Ultimate-D, Super Shocker's most powerful monster.

He was last seen with his friends posing for a picture after the battle while continuing his adventures across the A.R. Worlds. }}

Kamen Rider G
"You are the only one who can save this world."

- Decade encourages G.

At some point during his travels across the worlds, Decade came through a dimensional wall to a world which was home to Goro (Kamen Rider G), who was having a hard time fighting a Phylloxera Worm. Decade told G, who recognised Decade, that he was the only one who could save his world. Decade was soon followed by the Nine Heisei Riders through the dimensional wall behind him. Kuuga and Ryuki gave G their words of encouragement, then all ten Riders called out to him. With a boost in confidence, G got up and destroyed the Phylloxera Worm with his Swirling Rider Kick as the ten Heisei Riders vanished.

Let's Go Kamen Riders
A mishap caused by the Greeed Ankh unintentionally altered the timeline which enabled Shocker to utilize the Core Medal to create the Shocker Greeed which defeated the Double Riders and seemingly erased the legacy of the Kamen Riders from history. In 2011, after Kamen Rider New Den-O's attempt to repair the damage, he along with Kamen Rider OOO and M-Ankh awaited execution. However, it was revealed the Double Riders had their brainwashing removed by a Shocker scientist.

The Double Riders joined with New Den-O and OOO to fight Shocker's forces, but were eventually defeated. When the order was given to kill everyone, V3 suddenly appeared, asserting that there were more than four riders. V3 was soon followed by all the other revived riders that came after him, as even though Rider history was changed, the people's memories haven't changed. Decade appeared after the three 90s riders and the first eight Heisei riders, defeating the Paradoxa Undead, Tiger Orphnoch and Shadow Moon in quick succession.

After the riders were united, they faced off against Shocker's Great Leader. Later, when joined by a force of extra riders, Decade got into his Machine Decader, and alongside all the other riders in their vehicles performed the "All Rider Break", ramming into the Rock Great Leader and defeating it once and for all.

Kamen Rider × Super Sentai: Super Hero Taisen
"Destroy all Super Sentai... or die trying!"

- his words as the leader of Dai-Shocker

Doktor G resurrected and gathered all defeated Rider villains, recreating Dai-Shocker. He told Tsukasa that the Riders and monsters needed to destroy the Super Sentai to ensure the survival of the Riders, and, answering that, Tsukasa took control of the new Dai-Shocker, becoming its Great Leader again to battle the Super Sentai and also the Dai-Zangyack, a new union of Super Sentai villains led by the Gokaiger's. As the Great Leader of Dai-Shocker, Tsukasa apparently destroyed many Super Sentai teams such as the Goseigers. Gokai Red (and ) was the last Sentai Ranger alive, while Decade himself was seemingly the last remaining Rider. After he was wounded in his battle against Gokai Red, Doktor G used the opportunity to overthrow him and take control of the organization. The story about Riders needing to destroy Sentai to survive was a lie, and Doktor G was actually allied with Dai-Zangyack and using both Gokai Red and Decade to destroy the other heroes and afterwards kill the nominal leaders of the two organizations.

However, Tsukasa and Marvelous already realized that trap from the beginning before the war starts. The destruction of the Super Sentai actually just an act and the truth was, all the Super Sentai and Riders were just sent into a rift between dimensions. Tsukasa turned against Dai-Shocker and Dai-Zangyack, supported by all other Riders and Super Sentai. Alongside the Gokaigers, he killed General Shadow. In the end, he faced Doktor G, the man behind the new Dai-Shocker, and defeated him with the help of the Super Sentai team, and Kamen Riders Ryuki and Blade. However, after being defeated, Doktor G was revealed to be Decade's old enemy, Narutaki, who escaped afterwards, and his real identity was left a mystery. After the battle, Tsukasa reconciles with Daiki accepting his friendship before the latter takes his leave.

Kamen Rider Murder Mystery! You’re the Great Detective!
The Kamen Rider Club celebrates the film Super Hero Taisen as they enter the Rabbit Hatch. Shun Daimonji is shocked to discover the body of Kamen Rider Decade on their common table, with multiple cards stabbed onto his helmet. As the club ponders a hypothesis, Gentaro considers it might have been, to which the ranger arrives and denies any connection, suggesting it may , who in turn implicates. Another body is discovered- this time Kamen Rider Double. Kamen Rider Meteor arrives to "help" the investigation. However, this time, an Imagin is found, Momotaros with a peach cup in hand. After Fourze gathers up the clues, he thinks that it is neither one of the Red Rangers, but instead it is one of the staff members that are currently filming them. Fourze started to think that Decade, Double, and Momotaros have something in common: they are all have the same suit actor (Seiji Takaiwa), which leads him to the culprit who is Eitoku. Fourze then noticed that in the Kamen Rider Series, Eitoku portrays the majority of the suit acting of the secondary characters (Urataros in Den-O and secondary Riders from Decade to Fourze) and knows that he wants to kill Seiji for taking the lead role, but the Riders that he killed weren't suit acted by Seiji, instead by other suit actors as Fourze reveals to him that Seiji is currently suit acting Fourze. After Eitoku is arrested, the deceased Riders revealed to be alive as they all go out for lunch and Kamen Rider Faiz calls to make reservations.

Decade later appears in another segment where his Complete Form Mode appears alongside Gokai Silver's form, Gold Mode as one of the similarities between Decade and Gokaiger.

Super Hero Taisen Z
, alongside Kamen Rider Beast and invaded the fortress of the Space Crime Syndicate Madou on Earth. However, inside, they're overrun by the forces of Space Shocker, which had allied itself with Madou. Gavan was separated from the others and trapped by Shocker's forces, when Kamen Rider Kamen Rider Fourze arrived, answering the call for help of, who asked for reinforcements to help in the attack. Fourze brought with him more allies, including Meteor, Super-1, the Super Sentai teams, and Decade himself to confront Space Shocker. Decade briefly fights against Tortoise Undead and afterwards pierces through a Pteranodon Yummy.

Afterwards, Decade presumably stays fighting against the other reinforcements brought by Space Ikadevil, while Fourze is thrown out of the area. Space Ikadevil himself is finished by the Super Sentai team Gokaiger, while Gavan and Meteor leave to fight against Space Shocker's and Madou's leaders. After the battle is over, Decade appears on top of a nearby cliff alongside the other heroes who appeared to help to say goodbye to Gavan and the others.

World Within the Magic Stone
"Someone once said...we don't fight for justice. We...fight for human freedom."

- Tsukasa telling Amadum what the Riders fight for.

Decade was summoned along with OOO by the alternate version of Haruto, taking the children to the shop. Before taking the children away, he thinks that he has arrived in the World of Wizard, but Haruto tells him that he is mistaken. He is summoned again by Amadum to retrive back the Fourze Rider Ring from Haruto. He then teamed up with Haruto along with the Heisei Riders to fight Amadum and his monsters. However, Amadum was too powerful for the Riders as he takes their items from them, until Gaim arrives. Gaim easily beats Amadum up as the Riders regaining their items to transform into their final forms. After Amadum is defeated, and the Rider Rings gone, Tsukasa leaves to continue his journey, stating that Haruto and him will meet again.

Kamen Rider Taisen
"It's true that I travel the worlds, and met many friends... And some of them are already dead, But I won't forget them. I keep them eternally in my heart."

- Tsukasa & the Heisei Riders confronting 1 & the Showa Riders.

Tsukasa managed to find Kouta in Drupers, telling the young Rider that he somehow knew Shuu before Narutaki appears to them. He warns the Riders about Badan's plan and the situation between the Riders from both eras, having Kouta become curious about it. Tsukasa would plan to gather the Heisei Riders as Kaito decides to join him. He takes Kaito to Futo, meeting up with Shotaro at the Narumi Detective Agency as he offers the young Rider to help the detective on his case. Later, Tsukasa approaches Takumi, asking him to join the battle against Badan. Takumi refused until he was attacked by Badan's monsters. He arrived to fight them until Kamen Rider Fifteen appears to attack him before Decade retreats. Meeting up with Shotaro in Futo, Tsukasa asks the detective to join the battle against Badan and Shuu's origins, which Shotaro would inform him about the boy. Tsukasa went to the lighthouse as he noticed that his mother, Saki looking at the picture with the note that Shuu wrote as she blamed herself for his death. Decade arrived where Shuu was and sent the boy to meet with his mother while Gaim distracts Fifteen. However, they were attacked by Badan's monster until Black and Black RX finished them off. Thanking both Riders, however their next target would be the Heisei Riders as Shotaro arrived to distract both Riders. Once they reached the lighthouse, Shuu was about to meet up with Saki, however Fifteen appears to retrieve his son as Tsukasa transformed to fight Fifteen. Overpowered by Fifteen, Gaim arrives to fight him, but failed to save the boy. Kouta was furious about Tsukasa not knowing Shuu's feelings. Tsukasa would gather the remaining Heisei Riders as Kouta and Takumi would join him. Once the remaining Riders arrive, both sides attack as Decade and 2 were defeated by each other. However all the Riders were freed thanks to Gaim as they started to battle the Badan Empire. Decade freed Shuu from the machine as the ship was destroyed by Wizard, Faiz, and X. After battling the Badan Empire, Hongo stated that their battle wasn't over as the Rider War continues. However the Showa Riders admit their defeat after seeing Gaim protecting a flower as they would congratulate the young Riders. Sometimes later, Tsukasa visits the lighthouse and looked at the photo of Shuu that he took.

Super Hero Taisen GP: Kamen Rider 3
Due to the timeline alteration caused by Shocker, Tsukasa became one of the brainwashed Riders in that timeline, donning the name of Shocker Rider Decade. Alongside Agito Burning and Hibiki, Decade joined Skyrider, Super-1, ZX and the Shocker Combatmen against the double agent Kamen Rider 3, providing his Ride Booker's firepower in a combined projectile assault before proceeding to physically overwhelm Rider 3 as he allowed Mach to escape.

On the following day, Decade was one of several Shocker Riders who volunteered in the Rider Grand Prix under Shocker Rider 3, who had been personally challenged by Kamen Rider Drive. During the race, Decade, along with Agito, OOO and Fourze, found that his Rider Machine, Machine Decader, had been immobilized by Mach's Signal Tomarle. Decade ultimately fell short of the Top 2 in which Drive prevailed over Rider 3.

Once Rider 3 was integrated into the Great Leader of Shocker's Rider Robo form, Decade was among the Riders who appeared to attack Zeronos Zero Form and Denebick Buster only to be fought off by the turncoat BOARD Riders: Chalice, Leangle, Blade and Garren. Ultimately, the Double Riders 1 and 2 made their appearance having survived their apparent demise from within the Rider Robo, and broke Shocker's brainwashing on the fallen Riders, enabling all Riders to unite in a final battle against Shocker.

Surviving the onslaught of the History Modifying Machine, Decade fought and destroyed Shocker's Schwarian with the Dimension Kick shortly before the Rider Robo was destroyed along with the machine by. Among the remaining Riders who witnessed the farewell of Kyoichiro Kuroi as the perversion of history was reversed, Decade's place in history was restored.

Kamen Rider Ghost: Legendary! Riders' Souls!
In the Youtube 6 part special, Takeru uses Decade's powers with the Heisei Rider Damashii. He also appears as a spirit in his and Specters' finisher along with the previous Heisei Riders.

Kamen Rider Ex-Aid "Tricks": Kamen Rider Genm
Despite not appearing in the web-exclusive series, Decade and 13 Heisei Riders were the projections of the Ganbarizing Critical Strike.

Chou Super Hero Taisen
An iteration of Decade Complete Form was summoned from the Game World as part of a team of five of the Strongest Kamen Riders alongside five of the  by Kamen Rider Brave, helping to defeat Shocker's army.

Kamen Rider Build: Be The One
Among the first 18 Heisei Riders, Decade fought against numerous monsters in a melee briefly witnessed by Sento Kiryu before being caught in the crossfire as Kamen Rider Zi-O BuildArmor used his Vortex Time Break to wipe out his enemies.

Kamen Rider Zi-O
{{#tag:tabber| Birth Of Zi-O=

Joining the Time Jackers And Battling Zi-O and Geiz.
"You want to become a king, right? But, that will never happen. I will destroy this world before you will."

- Tsukasa's warning to Sougo Tokiwa

Frustrated by Sougo Tokiwa's insistence upon befriending Geiz Myokoin, Woz allied himself with the Time Jackers and introduced them to Tsukasa, calling him a potential rival to Zi-O's reign but also a very capricious man. He first appeared using the power of Kamen Rider Agito to prevent Takeru Tenkuuji from catching Another Ghost, causing the Mysterious Phenomenon Institute to mistakenly blame Sougo and capture him. The next day, Tsukasa again intervened to protect Another Ghost, attacking Geiz and convincing him that Agito was allied with the Time Jackers.

Tsukasa intervened again the next day, fighting Zi-O and Geiz as Agito and later Kamen Rider Hibiki, which gave Another Ghost the opportunity to try and steal Sougo's soul. However, Takeru used his supernatural abilities to keep the Another Rider from absorbing the soul, leaving Sougo in a ghost-like state. Ora then asks Tsukasa if he desires to be a king, in which Tsukasa is not interested. It is then revealed that Tsukasa already has the Decade Ridewatch.

Tsukasa was soon back in action as Ora asked him to prevent Geiz from defeating Another Ghost in 2015, telling him to ride on her Time Mazine which Tsukasa told her that there was no need to rush as he used his dimension travel ability. Initially interfering with Geiz as Decade Ryuki, he soon transformed into Kamen Rider Ghost, and defeated Geiz. He took Geiz's Ghost Ridewatch and nullified it into a Blank Ridewatch. But for an unknown reason, he gave his Decade Ridewatch to Geiz with "an exchange" as his reason.

During the final fight against Another Ghost, Tsukasa only watched the fight. Woz asked calmly why he didn't join in which Tsukasa replied that he had understood Sougo enough. Tsukasa is also both confused and agitated by Woz's celebration announcement, to the point that he briefly stole Woz's Great Calamity Coming Calendar which annoys Woz. That night after the fight, Decade came to 9 5 DO, eating Sougo's dinner. Tsukasa introduced himself to Junichiro, Tsukuyomi and Sougo and takes a photo of Sougo. He then proceeds to tell Sougo that it's impossible for Sougo to become the Demon King as he would destroy the world before Sougo even became one before leaving.

During the battle against Kasshin, Tsukasa reveals himself to Sougo as both transform into their Rider forms. During the battle, Decade transforms into Kamen Rider Build as Zi-O transforms into DecadeArmor Build Form. Decade tells Sougo to go to the Year 2068 by using a Dimensional Wall to see Sougo's future self, Oma Zi-O.

Decade joins Kasshin in a battle against Zi-O and Geiz. During the battle, Decade transforms into Kamen Rider Wizard to counter Geiz in WizardArmor. As Zi-O and Geiz are fighting Kasshin, Decade suddenly leaves the scene.

Oma's Day=

Hidden Backstory of Sougo Tokiwa
As Heure revealed to Swartz, Tsukasa had told him about the Mirror World, and that he would find the Dark Shinji there. With this knowledge, Heure opened a gateway to the Mirror World and formed a contract with the Dark Shinji, transforming him into Another Ryuga.

Tsukasa appears again in the year 2009 as a bus driver, that transported a young Sougo Tokiwa and Hiryu Kakogawa. After Swartz causes the bus to go out of control and escapes with the children, Tsukasa escapes through a Dimensional Wall with Tsukuyomi from the exploding bus.

From there, they were transported to a near future where a Dai Mazine is destroying the city and witness Swartz select the young Sougo as a candidate to be king. Tsukasa then explains to Tsukuyomi that his objective is to observe all the happenings, and whether he'll fulfill his role to destroy this world.

Road To The King=

Space-Time Distortion
With the appearance of Ginga and Kamen Riders appearing alongside their Another Rider counterparts due to a fracture in the space-time continuum, Tsukasa steps in to investigate. He reveals to Swartz that he sees a connection between his and Tsukuyomi's pasts, and is determined to prove it. After being dared by Swartz to try to investigate, he personally brings Tsukuyomi to the year 2058.

In the year 2058, he and Tsukuyomi find a house, which is Tsukuyomi's house when she is younger. The two meet the younger Tsukuyomi inside the house. The younger counterpart freezes time, trapping both of them in place. A younger Swartz also shows up beside her before they both leave. It is here that they learn a shocking truth: that Tsukuyomi is actually the younger sister of Swartz. The current timeline's Swartz also makes his presence known, knocking out Tsukasa in the process. He tells Tsukuyomi to return and help Sougo and Woz deal with the meteorite. Tsukasa brings the girl back, as he quietly notes that he now understands Tsukuyomi's story.

Other Events=

Kamen Rider Heisei Generations Forever
Taking place before the Kamen Rider Ghost incident, Tsukasa joined the fight during the gathering of the 20 Heisei Riders with his usual Decadriver.

}}

Appearances in Other Media
{{#tag:tabber| Novel=

Kamen Rider Decade: The World of Tsukasa Kadoya ~The Garden Inside the Lens~
In the novel which is the reimagination of the TV Series, Tsukasa is generally the same personality wise. But his world is different from the world in Kamen Rider Decade: All Riders vs. Dai-Shocker movie. He has no sister and his parents live overseas. In the novel he’s described as a young tired of his mundane life, the only thing he finds interesting is photography. He ends up stumbling upon an abandoned photo studio, inside he finds an old camera standing on a tripod. Tsukasa picks it up and peeks through the viewfinder. Through the viewfinder, Tsukasa sees a completely different world. Instead of a flimsy Eijiro Hikari that knocks down a backdrop, the group uses the camera to travel between worlds. In fact, Eijiro doesn’t even exist in the novel. The photo studio isn’t some ordinary photo studio that was just abandoned. It actually manifests itself in front of people that are tired of their own world and want to find a new world. Natsumi, Kaito and Narutaki, all found the photo studio in their own respective home worlds. In addition, Dai-Shocker, the evil organization itself never existed.

Tsukasa met Natsumi in the first unnamed world he traveled to. A world where monsters are attacking humans. Natsumi sees this and calls Tsukasa by the name ‘Decade’ and gives him the Decadriver, telling him he must transform. A confused Tsukasa goes along with it and becomes Decade for the first time. They travel to another world together and meet Daiki Kaito. He acts hostile towards Tsukasa, but still decides to follow the two on their travels.

With 6 A.R. Worlds discovered leaving Den-O, Kuuga and Kabuto's World unexplored, the trio arrived at The World of Den-O with Tsukasa’s clothes change into a doctor’s uniform as they arrive. Tsukasa meets Ryotaro, but his Imagin friends are missing. Tsukasa agrees to help him find them. The Den-O characters feel very off-character as their characteristics are different. Momotaros comes off as rather polite compared to his jerkish and self-centered TV counterpart, and actually refers to people by their real names instead of snarky nicknames. The Final Form Ride remains the same, as Tsukasa turns Den-O into Momotaros.

Arriving at Kuuga's World, Tsukasa is dressed as a painter and meets Yusuke Godai while having difficulties of remembering the name Decade and usually goes with “Kamen Rider Dickens.”

Despite being Kuuga’s world, Tsukasa doesn’t interact much with Godai.

Instead he meets a mysterious unnamed girl, with her sentences spoken in broken grammar. This girl approaches different men saying “Do you want me?” The girl is referred as Yuri after Tsukasa sees her holding a lily flower, yuri in Japanese. She asks the question to Tsukasa, but Natsumi doesn’t like it and uses her Laughing Pressure Point technique on him. Yuri takes a liking to Tsukasa and connects with him. Tsukasa says they are the same type of people, and relate to each other. But he reveals that he never really paid attention to her and never cared about her. From the start, Natsumi oddly suspects that Yuri is a Gurongi. This is never truly touched upon until the where Yuri reveals the truth and challenge the Riders into a fight. Her Gurongi group is not mentioned, but she’s described as a Moth, meaning she's of the Ba class of Gurongi. She causes people to explode by sticking moth scales from her wings on people. Decade and Kuuga defeat her together. Decade's Final Form Ride for this Kuuga is also different: while it retains the ability to transform Kuuga into the Kuuga Gouram, the Gouram is described as a rhinoceros beetle, despite it traditionally being a stag beetle, which is also the same insect Kuuga is based on. Godai gives Tsukasa a thumbs up as they leave.

They shortly move onto the world of Kabuto, where they meet Souji Tendou, still as arrogant and confident as ever, and considers himself as the strongest Rider ever. The group enters Bistro La Salle where Hiyori Kusakabe works. Hiyori sees Kaito and Tsukasa, dressed as ZECTroopers, claiming that the two of them ate without paying. Tendou hears this and is enraged. The three of them fight and Tendou actually beats them with only a pair of chopsticks. However, it turns out to be a pair of Worms that ate without paying. Tsukasa and Kaito are eventually captured by ZECT, only to have Tendou save them. Tsukasa thanks him and says that he never thanks people. Tsukasa starts respecting Tendou. For some inexplicable reason, Tendou has the Clock Up Attack Ride Rider Card and gives it to Tsukasa after he realizes that he is Kamen Rider Decade. Tsukasa uses the Clock Up card as Kuuga, meaning the Attack Ride cards aren’t restricted to their respective Riders in the novel. In the end, the Worms that impersonate both Tsukasa and Kaito have been defeated. As the fight is over the trio goes back to Tsukasa's world.

Between all the traveling, a vampire has been attacking in Tsukasa’s world, leaving behind drained corpses. The group investigates and they find out that Narutaki is the vampire. Just like the group, Narutaki originally had his own homeworld, but abandoned it to find a new one. However, he’s been traveling for so long that his mind has been deteriorating and can barely remember who he really is. He was originally a human, but somehow in his journeys, he had lost his humanity. The Kamen Riders have a very pure energy that Narutaki seeks to consume: the Rider Cards. Thus, he sends Kaito to steal them for him. Kaito reveals his betrayal towards the team and gives Narutaki Tsukasa's 9 Heisei Rider Cards and Narutaki reveals his real form: a red-hued demon.

Kaito suddenly has a change of heart, and sacrifices himself to save Tsukasa. All hope seems to be lost; Tsukasa even uses a Diend card with the DecaDriver, which turns him into a cyan-hued version of Decade. However all seems hopeless, as he was badly overpowered by Narutaki and reverts into human form again. Natsumi, who had just realized that she has special powers all along, creates a special card with the 9 previous Heisei Riders on it. Tsukasa uses it, which summons the previous 9 Heisei Riders to do their finishers onto Narutaki. They then turn into cards and attached themselves onto Decade, turning him into Final Kamen Ride: Tsukasa, which can be described as Complete Form without a K-Touch. Tsukasa then finishes off Narutaki via a Rider Kick. In his dying words, Narutaki wanted to destroy all worlds and then create his own ideal world. He dies looking at Natsumi, knowing that she had the power to do what he wished for.

With the crisis over, Tsukasa returns to his world and Natsumi decides to go with him and live in his world. When they return, Tsukasa finds an article where it says Tsukasa's world's version of Natsumi died after committing suicide due to worldly troubles.

A few decades later, an unchanged young Kaito revives and reappears in front of an elderly Tsukasa. Kaito tells him it’s time to visit Natsumi’s world. There they are greeted by a young Natsumi, and Tsukasa finds himself as a young man again. Games=

Kamen Rider: Battride War
Kamen Rider Decade appears as a Main Rider in the video game Kamen Rider: Battride War, which unites the riders of the Heisei era from Kuuga to Wizard.

As in his series, Decade's primary skill is his ability to change into his nine predecessors using his Kamen Ride cards. In this state, he has access to some of their special attacks, though his strongest special remains the Dimension Kick (and using it will automatically revert him to Decade). His super form is Complete Form, and when activated he will perform a tandem finishing move depending on which Kamen Rider card is currently active. Decade Complete can perform a Final Attack Ride at any time by pressing R2 (the Final Form button) again, but doing so will cost energy and shorten the duration of Complete Form.

Decade's special attacks are:
 * Decade/Decade Complete: Attack Ride: Blast, Attack Ride: Slash, Dimension Kick
 * Kuuga: Uppercut, Mighty Kick, Pyrokinesis (Final Attack Ride)
 * Agito: Rider Punch, Ground Crash, Shining Clash (Final Attack Ride)
 * Ryuki: Strike Vent, Guard Vent, Burning Saber (Final Attack Ride)
 * Faiz: Sparkle Cut, Grand Impact, Photon Buster (Final Attack Ride)
 * Blade: Rushing Thrust, Serial Slash, Royal Straight Flush (Final Attack Ride)
 * Hibiki: Rekkadan, Spinning Rush, Ongekiken: Kishin Kakusei (Final Attack Ride)
 * Kabuto: Clock Up, Avalance Slash, Maximum Hyper Cyclone (Final Attack Ride)
 * Den-O: My Finishing Move, My Super Finishing Move, DenKamen Slash (Final Attack Ride)
 * Kiva: Sliding Combo, Barrage Punch Combo, Emperor Moon Break (Final Attack Ride)

Kamen Rider: Battride War II
Kamen Rider Decade reappeared in Kamen Rider: Battride War II, summoned by Cinema along with the remaining Heisei Riders in order to create the "ultimate movie". Decade's stage was based of from Kamen Rider Decade: All Riders vs. Dai-Shocker, with King Dark as his main enemy. Decade's Strongest Form is Strongest Complete Form, whose moves are identical to the original version.

Battride War II also introduces Decade Violent Emotion from Kamen Rider × Kamen Rider W & Decade: Movie War 2010 as a separate and distinct character. While the original Decade has the power to transform into other Kamen Riders, Violent Emotion instead gains the ability to use their signature attacks (including some which aren't available to the originals, like Blade's Deer Thunder). His strongest attack is the Dimension Kick, resembling the "homing" version he used against Skyrider in Movie Wars 2010.

Decade Violent Emotion's special attacks are:
 * Decade: Attack Ride: Gigant, Attack Ride: Slash, Invisible (ends with Dimension Kick)
 * Kuuga: Mighty Kick
 * Agito: Rider Kick
 * Ryuki: Strike Vent
 * Faiz: Grand Impact
 * Blade: Deer Thunder
 * Hibiki: Ongekida: Kaen Rendan no Kata
 * Kabuto: Clock Up + Rider Kick
 * Den-O: My Finishing Move Part 2
 * Kiva: Barrage Punch Combo

Kamen Rider: Battride War Genesis
Kamen Rider Decade reappeared in Kamen Rider: Battride War Genesis

}}

Personality
According to others, he was the ruthless and unforgiving leader of Dai-Shocker who easily tortured and killed people with little to no remorse.

As Tsukasa traveled between dimensions, his clothing changes to suit the Rider's World, including some accouterments similar in color to his camera and Decade. He also exhibits some prior knowledge or a talent necessary to his quest in the Rider's Worlds he enters. Some examples are his knowledge of the Gurongi language in Kuuga's World and his enrollment as a student in Faiz's World. He has also mentioned before that he is capable of doing anything except for taking photos. He also tends to tell American jokes from time to time that sometimes scares others. He is also quite cocky as he often taunts people from time to time.

However due to his travels, he slowly lost his memories and ended up in a world in with no clear goal in life. He became very hypocritical and self-righteous and possessed a strong desire to "catch the world" using his photos. Unbeknownst to him due to his status as an outsider of the world, his photos do not develop well and foreshadow his fate as the Destroyer of Worlds. It's because of this that Narutaki began to follow him to over worlds to spread a fact that Decade will one day destroy them all.

Despite having these less than admirable traits, Tsukasa still tries to save innocent people as Decade, while teaching both the A.R. Riders and himself a valuable lesson in life. He also seems to care for the people close to him as he saved his sister from Tsukikage's influence. He was also the one who helped give Shotaro closure as well as helped Haruto when he was in doubt.

After fully reclaiming his memories, his personality gained qualities of both his old and new selves. Instead of outrightly claiming that a world needs to be destroyed, he now closely observes the events of the worlds to determine whether it is required to destroy it or not, even looking into its past and future, like what he began to do in World Of Zi-O due to possible emergence of Zi-O into Oma Zi-O. If required, he may also temporarily ally himself to the villians of that world without them knowing his true motifs. However, he still maintains his heroic nature whenever he needs to fight the evil himself.

Before a climatic battle begins, Tsukasa answers a major villain's demand for his identity by saying that he is "Just a passing-through Kamen Rider, remember that!" (通り過がりの仮面ライダーだ、覚えておけ！).

Tsukasa uses a "Decade Pink" Blackbird Fly 135 .

Powers and Abilities

 * Reality Alteration (Uncontrollable): His presence causes all of the A.R. Worlds to merge with one another, erasing those worlds and its people as a result, though this is not by his own will. This has stopped since his initial death at the hands of Natsumi, and does not seem to continue after his resurrection. He can also uncontrollably insert his existence into any reality he visits, making people of those reality already know him from the start, such as when he did it in the World of Blade.
 * Self-resurrection: If people still remember him, he can be resurrected from the dead..
 * Peak Human Physicality/Reflexes: As the former leader of Dai-Shocker, it is presumable that Tsukasa was skilled at fighting even before the start of his series. In fact, it seems that Tsukasa's abilities far surpass a normal human since he defeated two high level Orphnochs in tennis and used a card as a shuriken to cut a chain. In theory, it is possible that Tsukasa may not be a normal human as he was the Great Leader of Dai-Shocker with most of the High Ranking Members being powerful creatures and cyborgs themselves.
 * Enhanced Memory: Even after losing his previous memories, he could easily fight against most of the A.R Riders while holding back. By transforming into Decade, he could seemingly use all of the other main Rider's powers (even when he had no idea of how his Rider System and the previous Rider Powers work while not able to use them as effectively or skillfully as the originals, but can turn it into his own style) and fight against his former subordinates as well as other monsters.
 * Extremely High-Level Intellect: He is very calculative, cunning and manipulative, he became Leader of Dai-Shocker when he was young, outsmarted many villains, easily manipulates Dai-Shocker and Zangyack alongside Captain Marvelous. Very quick at infiltrating parallel worlds with limited information on those realities, which led him to solve many problems.
 * Dimensional Travel: An otherworldly human himself, Tsukasa can travel within worlds via Dimensional walls. However, the downside is that he is unable to take pictures perfectly in the world he resided unless if he is in his true world. Also to be noted is that the people taken by said pictures often suffer in one way or another.
 * Dimensional Sending: Can send people into Dimensional rift, a space between worlds, with just one swing of his sword.
 * Time Travel: Tsukasa is seemingly able to travel to different periods of time via the Dimensional Walls, as performed when he follows Geiz to 2015, and previously when delivering Sieg to Onigashima in the Muromachi period.
 * Nine Worlds abilities: Due to having no real home of his own, whenever Tsukasa travels to another world, he takes on a role within it, granting him different abilities as well as all necessary needs to take on that role (IE clothes, hairstyles, document setc.). Among these abilities are:
 * Gurongi Language Interpretation: In the World of Kuuga and Agito, Tsukasa showed the talent of understanding and speaking the Gurongi language.
 * Violin Knowledge: In the World of Kiva, Tsukasa showed that he has a talent of playing a violin solo similar to those of Otoya and Wataru Kurenai.
 * Mirror World Travel: In the World of Ryuki, Tsukasa can enter and survive within the Mirror World without the need of an Advent Deck. Normal humans would usually be dead once they tried to return to the real world.
 * Culinary Knowledge: Befitting his rank and job as a chef at the World of Blade, Tsukasa is given the talent of a great chef.
 * Lords and Seed of Agito Knowledge: In the World of Agito, he gained knowledge of the Unknown and the Agito Seed.
 * Clock Up Vision: In World of Kabuto, Tsukasa can see any ZECT Riders when they are in Clock Up, which is supposedly impossible to be sighted by normal humans due to them moving at near lightspeed.
 * Ongekibou empowerment: In the World of Hibiki, Tsukasa was given the ability to use the Ongekibou, as shown using it in a pair of Ongekibou Rekka.
 * Ridewatch Nullification: Tsukasa is capable of nullifying the power of a Ridewatch, nullifying the Ghost Ridewatch in front of Geiz.
 * Great Kamen Rider Knowledge: Tsukasa is shown to have a lot of knowledge related to any Kamen Rider, be it Riders of another world like Ryuga, Riders from the future like Oma Zi-O, as well as Kamen Rider Ginga.

Devices

 * Decadriver/Neo Decadriver - Transformation device
 * Rider Cards - Gives Decade the powers of Heisei and Shōwa Kamen Riders, depending on which card used
 * Den-O Belt - Transformation belt
 * Rider Pass - Gained by Decade when he enters World of Den-O
 * - Allows Decade to utilize the Tensou power of the, one was loaned to him by
 * K-Touch - Decade's device that allows him to transform into Complete Form
 * GaGa Armlet - Artifact granting ancient Incan power, temporarily acquired via Attack Ride: GaGa no Udewa before passing onto Amazon through Final Attack Ride: Amazon.

Weapons

 * Ride Booker - Decade's primary weapon and essential for holding Rider Cards
 * Rider Weapon - Weapons of past Kamen Riders accessed through Kamen Ride, Form Ride, and Attack Ride cards
 * Dragon Rod - Decade's personal weapon as Form Ride: Kuuga Dragon
 * Pegasus Bowgun - Decade's personal weapon as Form Ride: Kuuga Pegasus
 * Titan Sword - Decade's personal weapon as Form Ride: Kuuga Titan
 * Storm Halberd - Decade's personal weapon as Form Ride: Agito Storm
 * Flame Saber - Decade's personal weapon as Form Ride: Agito Flame
 * Drag Visor - Decade's personal weapon as Kamen Ride: Ryuki
 * Dragreder - Decade's summoned Contract Monster as Kamen Ride: Ryuki, accessed through Attack Ride: Advent
 * Drag Claw - Decade's personal weapon as Kamen Ride: Ryuki, accessed through Attack Ride: Strike Vent
 * Drag Shield - Decade's personal weapon as Kamen Ride: Ryuki, accessed through Attack Ride: Guard Vent
 * SB-555H Faiz Edge - Decade's personal weapon as Kamen Ride: Faiz, yanked from Auto Vajin (Machine Decader)
 * SB-555W Faiz Axel - Decade's stopwatch weapon as Form Ride: Faiz Axel
 * Blay Rouzer - Decade's personal weapon as Kamen Ride: Blade
 * Ongekibou Rekka - Decade's personal weapon as Kamen Ride: Hibiki, accessed through Attack Ride: Ongekibou Rekka
 * Kabuto Kunai Gun - Decade's personal weapon as Kamen Ride: Kabuto
 * Garulu Saber - Decade's personal weapon as Form Ride: Kiva Garulu
 * Basshaa Magnum - Decade's personal weapon as Form Ride: Kiva Basshaa
 * Dogga Hammer - Decade's personal weapon as Form Ride: Kiva Dogga
 * Gigant - Decade's personal weapon, originally used by Kamen Rider G4, accessed through Attack Ride: Gigant as Violent Emotion
 * Gan Gun Saber - Decade's personal weapon as Kamen Ride: Ghost
 * Flame Wizard Ring - Decade's personal weapon as Kamen Ride: Wizard. By activating Final Attack Ride: Wizard, the Flame Wizard Ring can perform the abilities of Wizard's Magic Rings.
 * Final Form Rides - Unique weapons transformed from past Kamen Riders through the Final Form Ride cards
 * Kuuga Gouram - Transformed from Kuuga via Final Form Ride: Kuuga Gouram or Final Form Ride: All Rider
 * Ultimate Kuuga Gouram - Transformed from Kuuga Ultimate Form via Final Form Ride: All Rider
 * Kuuga Ball - Transformed from Kuuga, exclusive to Kamen Rider Battle: Ganbaride
 * Kiva Arrow - Transformed from Kiva via Final Form Ride: Kiva Arrow or Final Form Ride: All Rider
 * Ryuki Dragreder - Transformed from Ryuki via Final Form Ride: Ryuki Dragreder or Final Form Ride: All Rider
 * Blade Blade - Transformed from Blade via Final Form Ride: Blade Blade or Final Form Ride: All Rider
 * Faiz Blaster - Transformed from Faiz via Final Form Ride: Faiz Blaster or Final Form Ride: All Rider
 * Agito Tornador - Transformed from Agito via Final Form Ride: Agito Tornador or Final Form Ride: All Rider
 * Momotaros - Transformed from Den-O via Final Form Ride: Momotaros or Final Form Ride: All Rider
 * Zecter Kabuto - Transformed from Kabuto via Final Form Ride: Zecter Kabuto or Final Form Ride: All Rider
 * Hibiki Ongekiko - Transformed from Hibiki via Final Form Ride: Hibiki Ongekiko or Final Form Ride: All Rider
 * CycloneCyclone and JokerJoker - Transformed from Kamen Rider Double via Final Form Ride: Kamen Rider W
 * Strong Zecter - Transformed from Stronger via Final Form Ride: Strong Zecter
 * Ongekibou Rekka - Temporary weapon loaned to Decade in the World of Hibiki when against Bakegani
 * - Temporary weapon lent by against Chinomanako
 * Decade Bazooka - Decade's firearm weapon that is only exclusive to Kamen Rider Decade: Protect! The World of Televikun
 * Colt M4 Modular Weapon System Carbine - Decade's firearm weapon that was given in the Alternative Zi-O's world.
 * Combination Armament DenGasher - A weapon used by Den-O that can be manipulable depending on the Imagin. While Momotaros in possession, his took the form of Sword Mode (ソードモード).

Vehicles

 * Machine Decader - Decade's Rider Machine
 * SB-555V Auto Vajin - Alternative machine form accessed through Attack Ride card as Kamen Ride: Faiz
 * SB-913V Side Basshar - Alternative machine form accessed through Attack Ride card as Violent Emotion, vehicle originally belonged to Kamen Rider Kaixa
 * New Cyclone - Alternative machine, presumably transformed from Machine Decader via Attack Ride card, as Kamen Ride: #1
 * Rose Attacker - Rider Machine loaned to Decade by Gaim in Kamen Rider Taisen

Family

 * Sayo Kadoya - Younger sister

Legend Rider Devices
}}

Portrayal
Tsukasa Kadoya is portrayed by Masahiro Inoue (井上 正大), who reprised his role in Kamen Rider × Super Sentai: Super Hero Taisen, the special episodes of Kamen Rider Wizard, Heisei Rider vs. Showa Rider: Kamen Rider Taisen feat. Super Sentai, and Kamen Rider Zi-O.

While disguised as Kamen Rider 1 in Kamen Rider × Super Sentai: Super Hero Taisen, he is voiced by Tetsu Inada (稲田 徹). In Kamen Rider × Super Sentai × Space Sheriff: Super Hero Taisen Z, Kamen Rider Decade's voice was provided by Katsuhiro Suzuki (鈴木 勝大), who plays in . 

As Kamen Rider Decade, his suit actor was Seiji Takaiwa (高岩 成二), who has been the suit actor for the majority of leading Kamen Riders in the Heisei era (except Kuuga and Hibiki). In Super Hero Taisen and Kamen Rider Taisen, his suit actor was Jun Watanabe (渡辺 淳).

Meme
A quote "This is also all Decade's fault!" and "Curse you Decade!" which said by Narutaki became popular due to Narutaki always blaming Tsukasa that it's his fault for whatever happens. This became popular when shocking news or just odd occurrences would happen.

Etymology
Tsukasa's name is a homonym of the phrase "user and card" (カードや使さ).

Rider No.
As the leading Rider protagonist of Kamen Rider Decade, Tsukasa Kadoya (Kamen Rider Decade) is labeled Kamen Rider #25 (仮面ライダー25号) and Heisei Rider #10 (平成ライダー10号).

In Popular Culture
''Haiyore! Nyarko-san episode 3 contains an extended reference to Decade'' in the rooftop lunch scene. Cuuko teases Nyarko with a cake from the legendary space bakery DK-Do, owned by a man named D. Endo. The cake is said to be a limited 10th anniversary special production, and is modeled on the Decadriver; additionally, when Nyarko explains about the bakery to Mahiro, its name appears in black and magenta stripes, while D. Endo's is represented with black and cyan. Later on, Nyarko transforms her pet Shantak-Bird into a motorcycle, with her remarking "This may tickle a bit. Heck, it'll only hurt for a moment;" in the light novels, this Final Form Ride-style forced transformation is explicitly stated to be one of Nyarko's unique special powers.
 * Additionally, Nyarko's favorite television show is Iron Striver, a tokusatsu show made on Earth that serves as an obvious homage to the Kamen Rider franchise. A brief segment of the show seen in the OVA episode "How to Defeat a Kind Enemy" shows it to mostly be based off of Decade, with the main character physically resembling Tsukasa and using with a card-reading belt that forms the word "StriveRide" to transform. Said segment also features direct quotes from Decade, with Striver telling the villains "Bring it on! I'll destroy everything!"