Ryotaro Nogami

"I don't have any energy left to faint!"

- after becoming Den-O and before boarding the DenLiner for the first time

Ryotaro Nogami (野上 良太郎) is a young man with a lot of bad luck. When he first appeared, he managed to lodge himself in a tall tree while on his bike after losing control and going up a fallen sign. He has even placed a name tag in his wallet so it can be returned to him when it is stolen. Despite his hardships, Ryotaro will help anyone in need if he has the ability to do so. He refuses to accept self-sacrifice as the only means to protect others.

As a Singularity Point, he can resist the control of an Imagin contracted to him, among other things, as long as he's conscious. Due to this unique attribute, he was given the power to become Den-O, a Kamen Rider who protects the timeline from the Imagins' actions. As Ryotaro continues on his mission, he meets more Imagin, each taking his body and using it as their own for the duration of their possession. Each of his personality changes affect the color of his eyes and some strands of his hair, changing its color to match the Imagin.
 * When possessed by Momotaros, Momo is in Ryo's body. His hair spikes up slightly with a single red streak and he gains more muscular definition and the physical strength to go with it.
 * When possessed by Urataros, Ura is in Ryo's body with the right words to woo women and convince almost anybody. His hair is straight and calm and has a single blue streak going through it. He also wears a pair of black rimmed eyeglasses.
 * When possessed by Kintaros, Kin is in Ryo's body. His hair grows such that he has a ponytail with a golden yellow streak through it. However, his increased strength often results in self-injury and clumsiness.
 * When possessed by Ryutaros, Ryu is in Ryo's body, incorporating dancing into everything he does. He grows one long purple and black streak of hair and is always seen wearing a brown cap. His reckless personality infests itself upon Ryotaro, and usually causes him to destroy whatever is around if he gets out of control. One such incident occurred during the events of Climax Deka when R-Ryotaro arrested everyone who he thought looked suspicious and was part of the "Evil Organization" advertised by Negataros.
 * When possessed by Sieg, though they never forged a contract, Sieg is in Ryo's body. His hair is styled in cornrows and has several white highlights with one longer white and black lock on the left side of his face, and a white feather boa appears around his neck.
 * While Yuto was removed from time, Ryotaro gained a contract with Deneb, Deneb is in Ryo's body. His hair grows out past shoulder length with two locks of hair on each side of his head. On the right side, the lock is a neon green with a darker green streak within it.
 * When abducted by Shiro and possessed by the Ghost Imagin in the events of Final Countdown, Ryotaro's personality is overwritten by the evil Imagin's will. His hair turns snow white as it grows out long and spiky with light-yellow cat's eyes.

Biography
The son of Shinichi and Kayoko Nogami, Ryotaro lost his parents while in childhood with his older sister Airi caring for him along with their grandmother, making visits to the closed down Milk Dipper that his parents owned. He kept the only picture of their parents with them until he lost it, feeling regretful of it since. He and Airi eventually re-opened the Milk Dipper with the aid of his sister's fiancé. However, when Airi's fiancé mysteriously disappeared a month before the wedding, resulting in Airi's current amnesia of everything related to the man, Ryotaro dropped out of high school to help his sister at the Milk Dipper, being burdened that his sister made herself forget about the fiancé and attempts to make sure she is not reminded and be hurt.

When he finds the Rider Pass, he unwittingly becomes the protector of time and space known as Kamen Rider Den-O, fighting the Imagin who traveled to the year 2007 to grant wishes and travel further into the past to change the future to their liking. As he is a Singularity Point, he is immune to the effects of changes to the past, and he can also resist the temptations of an Imagin, as seen with the hotheaded Imagin he named Momotaros, whose contract provides Den-O with a fighting form. He is assisted by the Singularity Point Hana as well as the crew of the Den-Liner, a train that allows him to traverse time in pursuit of Imagin. They are the mysterious Owner of the Den-Liner and the dining car's waitress Naomi. Along the way, he becomes contracted to other Imagin who give him the ability to access three of Den-O's other forms. They are the lying Casanova Urataros, the herculean and narcoleptic Kintaros, and the childish yet strong Ryutaros.

Ryotaro later identifies a mysterious man who has been following him through the past as his sister's fiancé Yuto Sakurai, but then meets a young man who calls himself Yuto Sakurai and his Imagin contract Deneb, the team that can become Kamen Rider Zeronos. Upon meeting Yuto, he begins to learn more about the nature of time and the Imagin, and is told by Yuto that protecting people is not as important as protecting time. Ryotaro does not believe this and feels that the two are one in the same, and he will do so, despite his own weaknesses.

Ryotaro also briefly meets the Swan Imagin Sieg who allows him to access another form, and later the evil Kamen Rider Gaoh who hijacks the Den-Liner to travel to the past to obtain the the Gaoh-Liner, leaving Ryotaro without memory of being Den-O for a while, meeting his past self as a result, until Gaoh takes him to the Tokyo of December 26, 1988, the day Ryotaro Nogami was born, in an attempt to erase him. To defeat him, Yuto travels in time to pick up three other incarnations of Ryotaro for Urataros, Kintaros, and Ryutaros to possess and aid Ryotaro in the "Climax Scene", destroying the GaohLiner and defeating Gaoh. In the process, while getting to see his parents firsthand, Ryotaro learns how "people's memories are time".

Upon his return to the present, Ryotaro learns that because he retains only the memories of fighting Gaoh as Sword Form while his past selves are incapacitated, he has no memory of fighting as Rod, Ax, or Gun Forms. This causes Urataros, Kintaros, and Ryutaros to all dissolve into sand, from which Ryotaro's feelings manifest the Climax Cellphone K-Taros. This restores the three lost Imagin, and gives Ryotaro access to the stronger Den-O Climax Form.

When Ryotaro's actions cause the Junction Point to manifest, his sync with the Tarōs starts to dissolve as a side effect, forcing him to fight as Plat Form. However, solving the crisis in advance, the Tarōs use their powers to create the DenKamen Sword so Ryotaro can assume the powerful Den-O Liner Form so he can fight on his own. Shortly thereafter, he meets the Singularity Point Kai, who seeks to make the Imagin's future the true future, by seeking to destroy the Junction Point, who is later found to be Ryotaro's sister Airi. As a result, Ryotaro falls into a trap set up by Kai to keep him from Airi, with Kintaros and Urataros sacrificing themselves so Ryotaro can return to the present. In the process, Ryotaro learns that his missing memory is tied to the true identity of the one who will ensure that the flow of time and space leads to the future without Imagin: his niece who is revealed to be Hana/Kohana.

After the final battle is over, Ryotaro is saddened by the supposed loss of the Tarōs, only to find out that they and Sieg, still existing due to their memories together, are hiding in a ditch attempting to surprise him. Ryotaro is overjoyed that they are all still alive and celebrates happily. With his mission to protect time from Kai and his Imagin finished, Ryotaro relinquishes his Rider Pass back to the Owner of the Den-Liner, thanking everyone for what they have done for him. As he rides his bike back to the Milk Dipper, he is greeted by all of the riders of both the Zero-Liner and the Den-Liner who bid him a final farewell before departing into the time stream. Ryotaro smiles as they pass by, knowing that he will meet them again someday in the future.

Later, when an Imagin named Negataros steals the Rider Pass from Owner, Ryotaro joins the newly formed Den-Liner Police to stop Negataros and his "Evil Organization", succeeding thanks to the aid of Kamen Rider Kiva. After the case was closed, Ryotaro and the Den-Liner crew keep the Den-Liner Police going just for kicks.

However, Ryotaro is forced to resume being Den-O when he is possessed by the Ghost Imagin for Shiro, using the Signality Point in order to travel into the past while having the possessed Ryotaro as his enforcer, Kamen Rider Yuuki Skull Form. But through Momotaros' aid, Ryotaro manages to regain control so he can let his Imagin partner in his body to purge the Ghost Imagin before they finish the Imagin off in Climax Form. But during the climatic final battle against the revived Imagin, Ryotaro, Momotaros, and Kotaro assume their rider forms to defeat Shiro when he becomes Yuuki Hijack Form.

After formally meeting his grandson, Ryotaro promises him he won't divulge any learned knowledge of the future as he takes Kotaro and Teddy home on the Den-Liner.

Decade Biography
With Ryotaro off investigating an error in the timeline, there is no one person with the Tarōs that has the power of Den-O and the Tarōs manage without a permanent body to use. Following the departure of Ryotaro, prior to Tsukasa and company entering Den-O's World), the Tarōs suddenly lost the ability to maintain their physical forms due to the actions of an unknown force that is altering their present at some time in the past. The alteration of the present also ended up de-aging Ryotaro a few years, making him a young boy/teenager as a result.

Seeing the Mole Imagin surfacing to be connected to it, Momotaros possesses Tsukasa to fight one. After being evicted from Tsukasa's body by Natsumi's pressure point, Momotaros attempts to re-possess Tsukasa, but ends up in the body of Yusuke instead. After Tsukasa manages to get Momotaros to talk back at the Hikari Photo Studio, M-Yusuke storms off to solve the mystery behind his world's crisis.

As he is trying to figure out why buildings are disappearing, M-Yusuke is confronted by Daiki who wishes to know where the DenLiner is, revealing a DenLiner Final FormRide Card in his possession that would supposedly allow Momotaros to regain his physical form. Momotaros refuses, and then begins a fight with Diend as Den-O Sword Form, escalating against him with Diend using Sasword and Saga to outnumber him before he is sent plummeting off of a building. He survives as Diend takes his leave for Momotaros to reconsider.

Elsewhere, as Tsukasa and Natsumi investigate Den-O's World by finding the DenLiner and use it to go back to the time it started, Urataros, Kintaros, and Ryutaros each possess Tsukasa, revealing that they were warned of Decade and believe he is connected to the disturbances in their world. When Tsukasa manages to force them all out, they take over Natsumi's body, each using her to fight Decade in their respective Den-O Form as Decade counters as Agito. During the fight, both Riders are transported to another dimension similar to where the Rider War took place in Natsumi's dream. The fight would ultimately end in a stalemate as the DenLiner picks them up. Upon entering, they are greeted by Naomi, Kohana, and Owner, who would talk to them about teaming up to solve the mystery.

After tending to his injuries from taking out another Mole Imagin, M-Yusuke is confronted by Tsukasa before he senses the Imagin he's looking for, the Alligator Imagin. Chasing him to the past, Den-O is nearly killed by the Alligator Imagin when Decade and Diend intervene, with Diend using his Riotrooper card to hold the Imagin at bay. Diend would once again offer Momotaros a true body of his own, but Decade somewhat defends Momotaros, regaining his access to Den-O's powers.

Through the modified Final Form Ride Card, Momotaros regains his physical form and, after a slight misunderstanding from Yusuke, takes out the Alligator Imagin by using Kuuga Gouram as part of his Finishing Attack. Although the crisis is over another occurs after Momotaros returns to the DenLiner, with the Tarōs disappearing and Momotaros ending up on Onigashima as part of the Oni Conquest legend.

Kamen Rider Battride War
Kamen Rider Den-O appears as one of the Main Riders in the video game Kamen Rider: Battride War, which unites the riders of the Heisei era from Kuuga to Wizard.

In the game, if some of the four Imagin forms (excluding Liner Form) were taking too much damage, they won't be available for Den-O to transform into until one form remained or Liner Form will be the only form left.

Den-O is the only Main Heisei Rider who has two finishers in certain forms like the two Main Neo-Heisei Riders, Double and Wizard, but unlike these two riders whose forms (FangJoker and Infinity Style) are separate, Den-O's Imagin (Climax) Forms and Liner Form are one.

Kamen Rider: Battride War II
Kamen Rider Den-O reappeared in Kamen Rider: Battride War II, summoned by Cinema along with the remaining Heisei Riders in order to create the "ultimate movie". Den-O's stage was based of from Kamen Rider Den-O: I'm Born!, with Kamen Rider Gaoh as his main enemy.

Forms
By swiping a Rider Pass across the SetTouch, Kamen Rider Den-O is able to pass through four forms, each with their own strengths and weaknesses. Each of the forms (excluding Plat Form, Climax Form, and Liner Form) is based on a specific mythological hero along with motifs relating to the respective legends. However, when any of the Taros uses the Rider Pass, they bypass the Plat Form to assume their respective Den-O Form.

Device

 * Den-O Belt: Transformation belt
 * Rider Pass: A device to scan on the belt
 * Climax Cellphone K-Taros: Transformation device to become Climax, Liner, or Super Climax Form

Weapons

 * DenGasher: Personal weapon
 * DenKamen Sword: Liner Form's primary weapon

Vehicle

 * DenLiner: Den-O's personal train
 * Machine Den-Bird: Den-O's Rider Machine

Portrayal
Ryotaro Nogami is portrayed by Takeru Satoh (佐藤 健) and by Takuya Mizoguchi (溝口 琢矢) as a child. Mizoguchi returned to portray the present-Ryotaro after the character was de-aged in Cho Den-O series.

Rider No.
As the leading Rider protagonist of Kamen Rider Den-O, Ryotaro Nogami (Kamen Rider Den-O) is labeled Kamen Rider #23 (仮面ライダー23号) and Heisei Rider #8 (平成ライダー8号).