Sougo Tokiwa

Sougo Tokiwa (常磐ソウゴ), alternatively spelt Sogo Tokiwa, is an 18-year-old (19 as of Episode 34) high school student (graduated as of Episode 29) who is visited by Tsukuyomi and Black Woz from 50 years in the future and learns that he is destined to become the tyrannical ruler of their time, Oma Zi-O. With this knowledge, he makes it his goal to be a great king through kindness by becoming Kamen Rider Zi-O (仮面ライダージオウ). However, Geiz Myoukouin is hellbent on killing him to alter the course of history, with White Woz backing Geiz up until his disappearance from the timeline.

Early Life
Sougo Tokiwa was born on April 28, 2000 to his parents, Sotaro and Namie Tokiwa. On April 24, 2009, just four days before his ninth birthday, Sougo and his parents took a trip on a tour bus that was also (unbeknownst to him), passengered by Hiryu Kakogawa and Tsukuyomi, and driven by Tsukasa Kadoya. About halfway through the ride, Swartz (from an earlier timeline) arrived and stopped the bus with his powers, later boarding it and sat at the back. Swartz resumed time once again and subsequently sabotaged the bus, causing Tsukasa to lose control. Sougo's father (and another father) confronted him, but they were overpowered by Swartz's powers and taken down. After Swartz froze the parents in time, Sougo confronted the Time Jacker, but was held hostage, causing Tsukuyomi to shoot at Swartz in an attempt to save him. However the shot ricocheted and hits Hiryu, and Swartz proceeds to teleport himself and the children to somewhere in the city. The bus explodes inside a tunnel, killing everyone on board except for Tsukuyomi and Tsukasa, who both manage to escape right before the explosion via Dimensional Wall.

Sougo and the children awaken and discover the city being attacked by several Dai Mazines. When Sougo attempted to save Hiryu from being crushed by falling debris, he distinctively summoned a series of pink katakana that slowed down time, allowing him to save the boy and disintegrate one of the Dai Mazines by sheer willpower alone. Realizing Sougo's potential to become king, Swartz approached the young boy and offered him the chance of a lifetime, to become king and protect the world from destruction. After Sougo agreed, Swartz (to some extent) modified his memories, which an adult Sougo would later recall his memory as a dream. Swartz then proceeded to place Sougo and Hiryu at the site of the crash, where they would eventually be rescued and recorded as the two only survivors. The two later were admitted to a hospital and put into the same room. After Sougo was discharged, he moved in with his grand-uncle, Junichiro Tokiwa.

Since the incident, Sougo has had a strong belief that he could become a king, much to the chagrin of his future friends and uncle. According to his uncle, this was so serious that Sougo did not have friends growing up, and was lonely for most of his childhood. At some point, Sougo received a toy robot and wrote WILL BE THE KING in English on the back of it. This robot would later serve as inspiration for Rento Makina, later known as Kamen Rider Kikai.

During his elementary school years, he became quick friends with Tsutomu Tsuzumiya due to their seemingly "absurd" dreams together. At one point, Sougo was playing at a park, however he had gotten hurt and no one helped him. An unnamed high schooler who he would later affectionally call "Miss Sailor" (who highly resembled Yuri Aso) came and bandaged him up before offering to play with him. Later as they departed, Sougo became infatuated with her after she called him a cute boy. Sougo would later confuse the identity of this girl with Yuko Kitajima.

During his teens, he attended Hikarigamori High School, excelling in history but poor in physics.

The Birth of Zi-O
One day, Sougo found a mysterious watch-like item that was on the seat of his bicycle, and after examining the blank item, Sougo laid down the blank item, then went on home while minding his own business. Later while bicycling down a small street up towards a stairway, a man in hood, holding a grimoire appeared out of nowhere, who told him that it would be a momentous day for him and to avoid the "red robot" before mysteriously disappearing.

He does indeed encounter the robot shortly after, run by a man in red and black attire and attacks Sougo. He is saved by a woman claiming to be from the future named Tsukuyomi in her Time Mazine. They seemingly travel back in time to 1671 Japan where she proves her legitimacy to him. Tsukuyomi warns Sougo that the watch he currently had possessed a tremendous amount of power and using it will make Sougo turn into the worst and lowest demon king, Oma Zi-O. Just before Sougo could reply, a fight occurs and Tsukuyomi decide to test whether Sougo is really Oma Zi-O or not by forcefully putting Sougo in the middle of the fight. The citizens proceed to throw Sougo to a river and doing so makes peace for themselves. Instead of lamenting his misfortune, Sougo is relieved to see that the group had reconciled, much to the citizens’ amusement. However, a red Kamen Rider, Geiz manages to tail them and the two retreat back into the Time Mazine.

When Tsukuyomi was being attacked by Geiz, Sougo gets kicked out of the mech and wakes up in a strange world with a huge wall in the horizon. As he ponders over this, a Smash attacked him but luckily Kamen Riders Build and Cross-Z appears to help. After revealing their names, Sento and Ryuga bring Sougo to the cafe Nascita.

As Ryuga drinks from a carton of milk, Sougo sees the expiration date and realized that he's indeed in the year 2017. Sento affirms that Sougo is indeed from the future since, after some analysis, Sougo's Ridewatch is different from any current technology. Before Sento can ask about the future, Tsukuyomi appeared and shot the three of them into unconsciousness using Faizphone X, in order to prevent Sougo from interfering with the past any more than necessary. He wakes up in his old home, believing it to be all a dream. Later, he encounters a monster with the similar look of Kamen Rider Build attacking civilians. He tries to stop him but is quickly subdued twice.

Sougo was approached by the prophet, Woz once again, who then tells him that he'll become an demonic king who will reign over the future. Tsukuyomi desperately tries to warns Sougo to not use the Ridewatch. However, after some quick thought, Sougo decides to not become a tyrant, but to become a beloved future demonic king, much to both Tsukuyomi and Woz’s surprise. After that, the blank Ridewatch revealed itself to becoming the Zi-O Ridewatch, then Sougo is given the Ziku-Driver by Woz to transform and battle the elusive Kaijin Rider. As it is his new beginning of becoming a Kamen Rider, Woz announced the introduction of Sougo as he was now Kamen Rider Zi-O, the Time King, much to Tsukuyomi’s disappointment.

He is able to go on par with Another Build and is quick to defeat him using the Zikan GiLade finisher. Geiz enters the fray, seemingly frustrated with Sougo on his decision and Tsukuyomi as she failed in convincing him. Geiz proceeds to ask why Sougo became Zi-O, which the latter replied that it was probably decided from the moment he was born. Reminiscing Oma Zi-O’s declaration, Geiz deems Sougo as irredeemable and transforms using both Geiz and Ghost Ridewatchs to become Kamen Rider Geiz GhostArmor and advances towards Zi-O.

The Genius Physicist & Obtaining Build's Power
Geiz proceeds to attack Zi-O relentlessly until Tsukuyomi piloting the Time Mazine and tells Zi-O to run. After a lenghty bike chase, he manages to do so. Sougo then encounters Woz once more, who formally introduces himself. He states that the two that hail from the future are trying to change the future. Woz then warns him a group named the Time Jackers who have the same goal but to have another king of their choosing in the future. He claims to be the one keeping the timeline the same and that he's on Sougo’s side, remarking that his conquest has only just begun. He later finds Another Build fighting Geiz and rescues the two. With his Time Break, Zi-O seemingly defeats the monster once more, only to find it again within seconds. Believing the real Build could defeat him, he rushes off to find him.

Later, Sougo went to the same cafe to meet Sento and Ryuga again. However, due to Another Build's appearances, Nascita's scenery had changed, the fridge that was the passway to the Build laboratory is gone and both Sento and Ryuga become Tsunagizu fanboys instead, seemingly forgetting their memories of being Kamen Riders and their encounter with Sougo the previous year. After Geiz destroys Another Build once again, Sento and Ryuga memories returned, and two blank-ridewatches that they somehow possessed turns into the Build and Cross-Z Ridewatches. Sento then said to Sougo to take care of his past self and gives him the Build and Cross-Z Ridewatches. Although he doesn't understand at first, he quickly realizes that Another Build showed up and attacked Sento and Ryuga in 2017 and Sougo went back in time to help defeat it. He meets up again with Geiz and Tsukuyomi informing them and the two Riders head to their Time Mazines and head back to the past.

Sougo and Geiz manage to arrive at the very scene, only to be interrupted by Uhr of the Time Jackers. He tells Sougo that the host of Another Build's fate was to have his athletic career abruptly ended in an accident and that he helped him move forward. The latter argues that despite his ability to time travel and intervene with other's lives, it's that individual that can determine his or her future. Impressed with his statement, Uhr wonders what "his" future will look like and walks away. The two Riders transform and join up with Build and Cross-Z to take down Another Build. However, the change of events in the timeline has caused Build's and Cross-Z's powers to disappear, seemingly to have transferred into the Cross-Z and Build Ridewatches. Zi-O uses the Build Ridewatch to become Zi-O BuildArmor, with Woz appearing and remarking this moment. Zi-O Build Armor now able to damage the monster, with Geiz subduing him with his Zikan Zax in Yumi Mode. Zi-O uses Vortex Time Break to finish the monster with Geiz utilizing the Zax's finisher equipped with the Cross-Z ridewatch. Remembering that Sento and Ryuga gave Sougo the Ridewatches, he asks the two to hold on to two blank Ridewatches for safe keeping. Sento corrects him by saying that his real name is Takumi Katsuragi, and he seems to forget about Sougo. Geiz demands to know what's with sudden anomalies in the timeline, but Sougo himself is confused about it as well, only exclaiming that Sento and Ryuga will choose to become Kamen Rider Build and Cross-Z in the future.

Sougo wakes up the next morning to find out that Tsukuyomi and Geiz have rented out that his uncle's spare rooms. Tsukuyomi explains that him saving the two has questioned whether or not he will grow to become a vile dictator and have decided to keep an eye on him, with Geiz later saying his vendetta towards him hasn't ceased. Despite all this, Sougo seems to be fine with the two living under the same roof as him.

Genius Gamer M & Obtaining Ex-Aid's Power
"With No Continues... I think I'll clear this"

- Zi-O verison of Ex-Aid's proclamation The first day that Geiz and Tsukuyomi took a class with Sougo, Sougo didn't feel relax a bit because whatever he did, they would follow and sneak on him, especially Geiz took a look at him closely when he was about to use the toilet. During the lunchtime, he hid inside the sport warehouse and met a student playing a game from GENM Corp, similar to Mighty Action X game. However, when Sougo tricked the gym teacher for covering the student to play the game in quiet, Another Ex-Aid appeared and attacked the player. Sougo transformed and fought it, but after he got thrown, Another Ex-Aid disappeared. Geiz and Tsukuyomi came to Sougo and explained that it wasn't his fault and Another Rider had appeared.

At home, Sougo thought to play the game to lure Another Ex-Aid, but his skill was beyond help as he couldn't reach the level where the student would be attacked. Tsukuyomi said about if only there was a gamer which could help as even she and Geiz couldn't play any old video game, Sougo rushly caught an idea to search a gamer and went to search for Genius Gamer M after Tsukuyomi took a look on her history tablet. Sougo late to realize if doing things like running around to search for him was 100% a difficult task but he got tired after he had done that. But he found another victim and Another Ex-Aid escaped in a blink, with Sougo couldn't even reaching for it. Woz came and told Sougo to take the victim to the doctor.

Sougo, Geiz, and Tsukuyomi took the victim to Seito hospital. There, Sougo heard of a doctor who played games with the name of Emu and asked where he was. Hiiro met them and asked about the ruckus and Sougo told him of what he wanted. Hiiro recalled about Emu was missing after he played the mentioned game after Sougo revealed that the incident of the disease was related to the game. There was a note and Hiiro as he claimed that he somehow could trust them, on playing the game. The note was written in the German language and Geiz able to read it, revealing that it was a code for the player when they played the game. Sougo realized the meaning of the code after Geiz translated it and played the game, making them to be dragged to the game world itself and encountered Another Ex-Aid.

Sougo and Geiz transformed and fought Another Ex-Aid, who proved formidable until they transformed into Zi-O Build Armor and Geiz Drive Armor respectively to defeat it. Emu appeared and congratulated them on cracking his code in a cold tone, before transforming into Ex-Aid and attacking them.

Reaching the Stars & Obtaining Fourze's Power
In 2018, Sougo finds out that several high school girls are missing, and Tsukuyomi mentions that an Another Rider is maybe behind this. Sougo, Tsukuyomi, and Geiz then go to Amanogawa High School, where the last victim last seen. Indeed, in there they met Another Fourze attacking a girl. After repelling the kaijin, Sougo and co. are forced to go to the Kamen Rider Club. The club's temporary advisor, Chuta Ohsugi then gives Sougo the Fourze Ridewatch, that he got from the club's official advisor.

King Kuroto Dan & Obtaining OOO's Power
In 2018, Kuroto Dan, the head of the Dan Foundation, established his own country, dubbing himself 'King Kuroto Dan', after accepting a deal from Uhr in 2010 to become Another OOO. After Geiz goes to investigate and gets his hands on the Gemn Ridewatch (Kuroto's old rider form) in 2016, Sougo decides to go a different route and becomes the head of Kuroto's army.

Later on, Sougo met Eiji Hino, the past Kamen Rider OOO (erased because of Another OOO), who had become a politician and was imprisoned by Kuroto. Eiji gave Sougo the OOO Ridewatch, with Sougo becoming Zi-O OOOArmour to defeat Kuroto.

Time Paradox & Obtaining Gaim’s Power
While Sougo was facing Another Gaim in 2013 to save Geiz, he suddenly found the Gaim Ridewatch from nowhere and became Zi-O Gaim Armor, with a bit of difficulty. Eventually, Another Gaim was defeated, but suddenly, a mysterious entity pulled Sougo to an alternate dimension, eventually revealed to be Kouta Kazuraba (the old Gaim) as the The Beginning Man. He asked whether it was right to depend on his own power to save his friend, before sending Sougo back to 2018.

Going Limbo & Obtaining Decade’s Power
After defeating Another Gaim and saving Geiz from the Helheim Forest, Sougo went into the city to stop Another Ghost, who was sucking people's souls away. However, when he attempted to defeat him, Tsukasa Kadoya, the world destroyer working with the Time Jackers, stopped him and nearly made him lose his soul to Another Ghost. However, Takeru Tenkuji, the original Kamen Rider Ghost, was able to stop his soul being sucked away, leaving his soul displaced from his body and invisible to everyone but Takeru as he had the Ghost Ridewatch.

Geiz, realizing what had happened, went back to 2015 to fight Another Ghost, but just before he could be destroyed, Tsukasa interveined and stopped him again, giving him the Decade Ridewatch after neutralizing the Ghost Ridewatch. Sougo's soul was soon reunited with his body, and he became Zi-O DecadeArmor before regaining the Ghost Ridewatch, defeating Another Ghost while Tsukasa made his leave.

That night, Sougo returns home only to find Tsukasa at his dinner table, who threatens to kill him before he can become king.

Sent to the Future & Encounter with Oma Zi-O
The next morning, Sougo arrived to the dinner table, only to have Geiz attempt to convince him to stop being a Rider, but Sougo retorts the advice and starts eating. After Woz arrived and led Junichiro out the room, he informed the team of a crisis that was happening outside.

They head out and discover the Dai Mazines attacking areas all around the world. Sougo reveals that he had dreams as a child where the Dai Mazines attacked the city, but was approached by a mysterious man who told him he could stop it all if he became king. Later, one of Oma Zi-O's lackeys, Kasshin appears and is tasked with killing Geiz and Tsukuyomi to protect "Sougo". The two escape, but Sougo manages to find them later at a warehouse, where Geiz arms himself to fight Sougo with a new resolve. However Kasshin appears and assaults Geiz, who Sougo tries to tell that Geiz wasn't the enemy. Kasshin does not listen, and prompts Sougo to transform and stop him. Before he is able to do anything, Tsukasa appears and transforms into Decade. Sougo begged Tsukasa to stop so he can save Geiz, but Tsukasa did not let him and accessed Build form. Sougo did the same and went to DecadeArmor BuildForm, and the fight continued. Kasshin intervened, and Geiz decides to team up with Tsukasa who then attack Sougo and Kasshin. Sougo spends the rest of the fight in denial, only enhanced by the taunts of Tsukasa who then opens up a portal to 2068 and forces Sougo in, with Tsukuyomi following him in.

Sougo awakens on dystopian lands and discovers the stone monument of his first transformation, with Tsukuyomi confirming that he is in 2068. Sougo decides to walk around and see what the world was like, and is distraught to find that the remaining 50% of the population are living in poverty and the terror of Oma Zi-O. The two are then transported by Dragreder to the presence of Oma Zi-O, who reveals himself to be the person Sougo had feared to be. In both disbelief and denial, Sougo transformed and attacked his older self, who then survives the attack and transforms into Oma Zi-O. Oma Zi-O laughs in nostalgia, having not seen his default form for over 50 years, and attacks the young boy. Oma Zi-O then promises Sougo that one day in the future, he will gain powers befitting of a demon king. This angers Sougo as he goes into DecadeArmor and attacks Oma Zi-O with a Kuuga attack from his Ride HeiSaber, but Oma Zi-O whips out the Kuuga Ridewatch and counters it, sending it back to Sougo. Sougo gets up and readies a Kiva attack, while Oma Zi-O activates the Kiva Ridewatch and counters the attack once again, sending it back. The two do the same with Ryuki, and Sougo goes down once again. Oma Zi-O then tells Sougo that there is one thing he can do to prevent destruction and to not be a demon king, and that was to throw away his Ziku-Driver. He then shows Sougo what was going on in 2018 and sends him and Tsukuyomi back.

Changing the Timeline & Meeting White Woz and Shinobi
After being traumatized by his encounter with his future self (as Oma Zi-O), Sougo gave up on being Zi-O to stop the future from happening, while Kasshin came from the future to kill Geiz and Tsukuyomi, under orders from Oma Zi-O. Eventually, Geiz convinced him that he could still change his fate, despite the risk of Oma Zi-O's timeline occurring, and reassured him that if he started to stray towards that path, he would stop him before he went too far. Sougo then accepted his fate, becoming Zi-O once again as Decade Ex-Aid Form, killing Kasshin and helping Geiz destroy Uhr and Ora's Time Mazines. However, they both escaped.

As Sougo gave up his powers temporarily, this created a new timeline where Oma Zi-O doesn't exist, and from it came a different version of Woz, who would later be dubbed the White Woz. White Woz revealed himself to be loyal to Geiz instead of Sougo, calling him 'My Savior', or 'Geiz Revive', and that he had the ability to become a Kamen Rider, as Kamen Rider Woz.

The Mirror World, Accepting Fate, and Zi-O II
Following the Another Quiz incident, Sougo and Geiz finds themselves pursuing the elusive Another Rider,Another Ryuga, whose reflection powers were a challenge for the Kamen Riders. After numerous encounters, the group discovered that Another Ryuga was targeting persons associated with the ORE Journal news site. Following this lead, the team tracked down the former chief editor, who directs them to Shinji Kido, the original Kamen Rider Ryuki where they discovered clues about Another Ryuga's power.

The day after devising strategy, Sougo's uncle, Junichiro, presents Sougo with an unusual Ridewatch, which Black Woz had commissioned him to fix some time ago. Black Woz explains to Sougo that the Ridewatch was originally intended to be used by him on Oma's Day, but White Woz's present interference prompted him to make it available sooner. When Another Ryuga resurfaced, Sougo arrived in time to save Geiz from Another Ryuga. When using the new Ridewatch fails, Sougo is transported to the Mirror World along with Another Ryuga while trying to apprehend him. There, he encountered his Mirror World counterpart and a fight ensues.

Sougo and his Mirror World counterpart fight in their transformed state where Mirror Sougo accused him of being a hypocrite for his views before sending him back to his reality in defeat. Following the encounter, Sougo sought out the advise of Shinji Kido, the original Kamen Rider Ryuki, who survived his own encounter with Dark Shinji. After speaking with the former Rider, Sougo came to a realization and confronted his Mirror World counterpart once more. From his talk with Shinji, Sougo accepts that he may become the foretold Oma Zi-O despite his best efforts, but more importantly, he came to understand the importance of accepting one's self--the light and dark (represented in Mirror Sougo). Mirror Sougo offers his real world self a Ridewatch, which Sougo realizes was the missing component to the one Black Woz gave him earlier. Once combined, Sougo acquires the completed Zio Ridewatch II as Mirror Sougo merges with him and unlocks the power to reverse time. Using this newfound power, he prevents Geiz's death. Sougo then transforms into Zi-O II and defeats Another Ryuga.

Yet despite the outcome, Tsukuyomi becomes concerned that Sougo has acquired power similar to that Oma Zi-O. Fearing that Sougo may inevitably become Oma Zi-O, she debates whether he should to be eliminated while Geiz remains conflicted and undecided.

Zi-OTrinity is Born!
"I-I feel like something amazing has just happened!" "Wh-What is this?" "For us to become one..." "Huh? Geiz and Woz are here, too?"

- Zi-O, Geiz, and Woz's reactions upon becoming Zi-OTrinity

Be The One
"I am Kamen Rider Zi-O. The demonic king with the powers of all Kamen Riders, or so I'm told."

- Zi-O introducing himself to Sento Kiryu. At some point in his history, Kamen Rider Zi-O joined a battlefield where the first 18 Heisei Riders were engaged in battle against their numerous adversaries. This event was also witnessed by Sento Kiryu, Kamen Rider Build, which was inadvertently transported to this location as a result of experiments with the White Pandora Panel he conducted at some point following his battle with Kamen Rider Blood.

Arriving in his Time Mazine, Zi-O disembarked and found Sento, who noted the name "Kamen Rider" on his mask. Revealing to Sento that he possessed the power of Build, Zi-O used the Build Ridewatch to assume BuildArmor as he entered the fray. After striking several monsters with his Drill Crusher Crusher, Zi-O quickly performed a Vortex Time Break which wiped out all the Riders' opponents while catching the prior Riders in the crossfire. Reverting to his default form, Zi-O was left with Sento, who questioned who the Rider was and how he had his power. Introducing himself as Kamen Rider Zi-O, Sougo proclaimed himself as the demonic king with the powers of all Kamen Riders, while acknowledging that he was going by the word of others.

As Sougo
Sougo is described as an ambitious young man with a strong desire to be king, though his definition for it changed once he discovered the existence of his tyranical alternate future self. This desire stems from a recurring dream he has had since his childhood, where a man in black, who would later be revealed to be Swartz, had encouraged him into becoming one in order to save the world. Because of his eccentric dream, Sougo did not have any friends growing up, with his sole companion being a toy robot, a fact that Junichiro would confide later with Tsukuyomi, saying both she and Geiz were the first friends he ever had. Soguo also exhibits fanatical admiration towards the presence of regal figures (i.e.: Kuroto Dan) and ordinary people who possess benevolent king-like qualities (i.e.: Eiji Hino), as he believes he can learn from individuals who have succeeded in their ascension and also understand what is needed for one to be a benevolent ruler, resulting in him becoming one step closer to accomplishing his own ambitions.

During the Another Ryuga incident, Sougo was confronted by his Mirror World self, who stated that Sougo will eventually become Oma Zi-O no matter what path he takes. Sougo became terrified and upset by this revelation, added in with the fact that White Woz had succeeded in turning both Geiz and Tsukuyomi against him. However with Black Woz's help, Sougo was able to come to terms with his inner darkness and decided to risk it all in finding out if he truly does become the evil tyrant he was destined to be.

Sougo is a peaceful and genuinely kind man at heart and will show compassion and empathy even towards people who have committed horrible deeds, such as Yuko Kitajima. He will gladly put himself in danger in order to cease a conflict, a trait even Tsukuyomi does not fully understand. He is also very trustful towards others, and had no doubt that Geiz would use the Wizard Ridewatch and defeat Another Wizard in 2012.

Sougo also shows an inability to come out with his feelings, hiding the fact he genuinely feels lonely after Geiz and Tsukuyomi leave and insists he's fine. It wasn't until Junichiro built up the courage to actually scold him over this, advising him to just come out with how he is feeling and tells him that those that cannot come to terms with their own pain and admit it will become rulers who cannot understand others' pain. He finally is able to come to terms with his loneliness and admit to Geiz that he has felt lonely without the two of them at 9 5 DO, and asks them to return home.

Sougo seems to have a verbal tic by adding "Feels like it" (気がする) at the end of most his sentences, mostly due to his optimistic approaches. Sougo is generally very friendly and trustful, as he trusted Geiz to

As a Kamen Rider
He also takes his duty as a Kamen Rider very seriously, fully understanding the responsibilities of his powers to protect others, a trait he believes kings should exhibit. His Mirror World self however says otherwise and does not believe that Sougo truly wants to be a "good" king, and tried to encourage him into unleashing everything. After seeing Oma Zi-O for the very first time, Sougo became terrified and willingly had his powers taken away to prevent Oma Zi-O from existing, even going as far to give up his dream of becoming a king. However Geiz manages to convince Sougo to take up arms once again, as he promised he will stop Sougo from walking the evil path and bring him towards his promise of becoming a good demon king. Despite Geiz later revoking this promise to outright kill him after receiving GeizRevive, Sougo continued to harbor an innate friendship with him, later using it to convince Geiz to retake his promise once again.

Sougo's upbringing as an amateur king gives him an intense focus, which extends to his combat prowess. In the ensuing confrontation with Geiz, Sougo displayed formidable combat skill and effortlessly defeated him, who is supposedly a trained resistance soldier.

Sougo tends to take the offensive more than the defensive when fighting, as shown when he usually kicks Rider Armors to make them attach to himself, unlike Geiz who let the Armors attach to the user automatically.

Skills

 * Vast Historical Knowledge: According to Tsukuyomi, Sougo excels in history, although Sougo can stumble on remembering some historical figures as Mondo Douan has shown to be more adept in this field than him.
 * Keen Manipulator:  Sougo has a talent for understanding how people would behave and subsequently exploiting people around him to do his bidding like how he tricked both Geiz and Tsukuyomi into watching Another Wizard's magic show with him and how he took advantage of Woz to make him cooperate with him and Geiz. Geiz considered his manipulative capabilities to be a serious threat and an indicator of his potential to become an evil demon king.
 * Timeline Protection/Manipulation: Upon acquiring the Zi-O II Ridewatch, Sougo became immune to any changes in the timeline and gained several abilities allowing to manipulate time as he wishes. These abilities can be performed in and out of Rider form, which implies that the Ridewatch's abilities were bestowed upon him directly. Tsukuyomi openly admitted to Geiz that Oma Zi-O has these abilities as well, which were what made him so fearsome. This caused Tsukuyomi to be paranoid of Sougo, resulting in her avoiding him.
 * Timeline Reversal: Sougo can reverse time, allowing him to redo a certain event and change the future. So far, he has performed this ability twice to reverse the deaths of two people. His first recorded usage of the ability was to undo Geiz' death from Another Ryuga, and the second time was to undo Tsukuyomi's death by Another Kikai. While Sougo has been shown to have only reversed events once, it's unknown if he can reverse it a second time in the case he fails to succeed in changing the timeline the first time.
 * Dreaming: Tsukuyomi theorizes that Sougo's dreams of the future causes him to subconsciously integrate them into the timeline, as evident of the events that transpire in present day while he is dreaming. However, to what extent Sougo has to the control of this ability is unknown. The first recorded usage of this ability was when he dreamt of Rentaro Kagura in the year 2022 and gave rise to Another Shinobi in the present day, The second time was when he dreamt of Rento Makina in 2121 and gave rise to Another Kikai in the present day. However these dreams are not entirely all-powerful, as Sougo can change his present day decisions in order to completely stop or delay the prophesied event from happening, as such when his dreams of the fated duel between him and Geiz on Oma's Day was averted completely.
 * Retrocognition: Sougo also has the ability to look into someone's past, though he isn't able to fully come to terms with this ability as of now. The first recorded usage of this ability was when he received an influx of Yuko Kitajima's memories, although he wasn't able to fully describe it.

Weaknesses

 * Poor Academic Performance: According to Tsukuyomi, Sougo is helpless in science and curricular subjects in school. This indicated when he first used the BuildArmor, and instead of proper equations, it simply listed sentences stating that he 'didn't know' or 'something I learned in grade school'. Sougo does however manage to pass his exams with an 82/100 and avoid dropping out, despite having snored through his actual studying. Despite so, Sougo is able to graduate.
 * Future Sight Exploitation: Zi-O II's future sight can be rendered obsolete by opponents moving at super-speed, such as Geiz Revive Shippu and Kamen Rider PunchHopper. However they can exploit this ability by attacking him fast enough to stop him from counterattacking on time, which so far has only been done by Geiz.
 * Another Zi-O: While Sougo is able to coexist alongside his Another Rider counterpart, they both also become liable against one another. While Sougo is the only one able to defeat Another Zi-O due to having the corresponding Rider power, Another Zi-O can do the same to Sougo as well under the same circumstances.

Forms
Kamen Rider Zi-O transforms by inserting the Zi-O Ridewatch into the right-hand side of the Ziku-Driver and spinning the Driver 360 degrees. He accesses Rider Armor (ライダーアーマー) forms based on previous Heisei Kamen Riders by inserting Ridewatches into the left-hand side of the Ziku-Driver.

Zi-O can execute a finishing attack known as the Time Break (タイムブレーク) by pressing the Ride-On Starter on their Rider Ridewatch and rotating the Ziku-Driver. Time Breaks performed in a Rider Armor are named after the respective Rider's special move with "Time Break" after it.

Devices

 * Ziku-Driver - Transformation device
 * Ridewatches - Transformation trinkets
 * Ridewatch Holder - A strap to carry Ridewatches

Weapons
Handheld weapons:
 * Zikan Girade - Zi-O's and Zi-OTrinity's personal weapon and Zi-O II's secondary weapon
 * Ride HeiSaber - Zi-O's personal weapon while using DecadeArmor
 * Saikyo Girade - Zi-O II's and Zi-OTrinity's personal weapon
 * Zikan Zax - Zi-OTrinity's personal weapon
 * Zikan Jaclaw - Zi-OTrinity's personal weapon
 * Zikan Despear - Zi-OTrinity's personal weapon

Suit-equipped weapons:
 * Drill Crusher Crusher - BuildArmor's personal weapon based on the Drill Crusher
 * Gashacon Breaker Breakers - Ex-AidArmor's personal weapons based on the Gashacon Breaker Hammer Mode
 * Booster Module - FourzeArmor's personal weapons based on the Rocket Module
 * Tora Claw Z - OOOArmor's personal weapon based on the Tora Claws
 * Daidaimaru Z - GaimArmor's personal weapons based on Orange Arms' Daidaimaru
 * Kamen Ride: Decade Card - In Ganbarizing, when Zi-O DecadeArmor and his Final Form Time utilizes Attack Time Break, he throws the Kamen Ride: Decade Card to his target and performs a variant of Decade's Dimension Kick.
 * Drag Visor-Zwei - DecadeArmor Ryuki Form's weapon

Vehicles

 * Ride Striker
 * Time Mazine

Relationships

 * Tsukuyomi: Tsukuyomi is the one that first informs Sougo about his future as Oma Zi-O. Initially believed Sougo as evil as the future Demon King, Tsukuyomi joins Geiz at watching Sougo's every moves. Eventually, as Sougo shows his kindly disposition, Tsukuyomi mellowed and became his most trusted ally. However, when he evolved into Zi-O II, she reaffirms her resolve that Sougo must be killed before ascending into Oma Zi-O. Since she believes that Zi-O II’s power to read the future is the same as Oma Zi-O. Despite her paranoia towards him, she can't bring herself to kill the younger Sougo and instead tries to save him from Swartz. After learning from Tsukasa that Sougo's fate as Oma Zi-O can be rewritten, Tsukuyomi starts to believe in Sougo again.
 * Geiz Myoukouin/Kamen Rider Geiz: Geiz strongly believes Sougo is Oma Zi-O and is absolutely determined to kill him before he could become the demon king to prevent the future where Sougo supposedly becomes the tyrant that rules all with an iron fist. He refuses to call Sougo by his real name and cruelly refers to him as Oma Zi-O. At many points in the show, Geiz shows Sougo hostility, but over the course of the story, he begins to realize that Sougo isn't as bad as he once thought. When Sougo finds himself in the future, Geiz even outright begs Sougo to give up the Ziku-Driver to prevent himself from becoming Oma Zi-O, showcasing that his resolve to kill him has lessened greatly, and perhaps even sees him as a friend. Geiz also initially hesitate when Tsukuyomi advised him to stay away from Sougo due to his Zi-O II power. Although this might be because Sougo has information about Kikai. After Geiz acquired Geiz Revive Ridewatch, their rivalry was renewed. But they also make amends after Tsukuyomi returns to them, alive and well.
 * (Black) Woz: With Woz having seen his future master's history and dreams to become king, Sougo is often baffled each time Woz appears aside from delivering his speech of passing Rider powers onto him by his predecessors. Despite even when Woz briefly sided with the Time Jackers to "correct" him, Sougo doesn't even seem to mind. Nevertheless, Woz remains a loyal servant and messenger towards Sougo.
 * Junichiro Tokiwa: Sougo's uncle. Junichiro always wanted Sougo to face reality and take tests to get into a university, but he still respects Sougo's dream to become king. Junichiro is also prone to giving advice to Sougo.
 * Future Sougo: His future self as Oma Zi-O. When Sougo first learned of him through Tsukuyomi, he initially didn't believe her. When he does believe her claim, he becomes determined to change his fate, but he otherwise still remains skeptical of how dangerous Oma Zi-O is according to her and Geiz. It wasn't until a proper meeting when he was sent to the future that he understood the reason why he was feared. Sougo despises what his future self has become, and is even more determined to change his fate.

Past Kamen Riders:

 * Sento Kiryu/Kamen Rider Build: The first senior rider Sougo met, Sento entrusted his past self to Sougo. They then fight together against the machinations of Super Time Jacker Tid.
 * Emu Hojo/Kamen Rider Ex-Aid:
 * Takumi Inui/Kamen Rider Faiz:
 * Kuroto Dan/Kamen Rider Genm/Another OOO: Sougo serves Kuroto to complete his ambition of becoming king, but soon betrays him because he believes that a king must care about people (which Kuroto does not). Sougo also thinks he is the only king the world needs.
 * Eiji Hino/Kamen Rider OOO: Sougo likes Eiji's view about helping people that are reaching out to him, and notes that Eiji has a kingly disposition too.
 * Kouta Kazuraba/Kamen Rider Gaim: Sougo meets the version of Kouta that ascended into the Man of the Beginning, and the space god teaches Sougo the most important thing to have as a king: a person he can fully trust.
 * Takeru Tenkuji/Kamen Rider Ghost: As Takeru is the only one that can see Sougo in his spirit form, Sougo trusted him to enact his plan at saving Another Ghost's host. Then, Takeru helps Sougo return to his body.
 * Tsukasa Kadoya/Kamen Rider Decade: Tsukasa provoked Sougo by saying that he will destroy his world. Tsukasa also sends Sougo into the year 2068 to witness his rule as Oma Zi-O. After being cornered by Zi-O and Geiz however, he escaped with the promise to fight him again in a foreseeable future. But, actually Tsukasa's true motive is to destroy Zi-O's world if he ever becomes Oma Zi-O.
 * Shinji Kido/Kamen Rider Ryuki:
 * Kazuma Kenzaki/Kamen Rider Blade:
 * Hajime Aikawa/Kamen Rider Chalice:
 * Daiki Kaito/Kamen Rider Diend: He appears suddenly to steal Sougo's Ridewatches, seemingly on White Woz's command. But actually he is Oma Zi-O's underling, and his true aim is White Woz's future tablet.
 * Shouichi Tsugami/Kamen Rider Agito:
 * Kyosuke Kiriya/Transformed Kyosuke/Kamen Rider Hibiki:
 * Tomizo Todayama/Kamen Rider Todoroki:

Others

 * White Woz: Being Woz from a different timeline where his future self was dethroned, the other Woz sees Sougo as a threat due to the fact that White Woz's loyalty lies with Geiz Revive. White Woz, however, doesn't see Sougo as a big hindrance, until Sougo becomes Zi-O II. Ironically, Sougo is the one behind White Woz’s redemption, to the point that White Woz willingly gives Sougo his Zi-O II Ridewatch, Geiz Revive Ridewatch, and the newly created Zi-OTrinity Ridewatch. White Woz also show his interest in Sougo’s possibility to alter the future to his counterpart, moments before he is erased from the timeline.
 * Hiryu Kakogawa: Hiryu thought that his parents were dead in a bus accident in 2009 because of Sougo, vividly remembering a woman in white dress aiming her gun at Sougo. Since then, Hiryu hates Sougo with a passion, even going as far to become Another Zi-O, just to kill him. Sougo then advises Hiryu to stop dwelling in the past and keep moving forward. However, their relationship is still shrouded in mystery.
 * Tsutomu Tsuzumiya: Tsutomu is Sougo's childhood friend, who dreams to become an Oni. Due to both of them having a seemingly 'absurd' dream, they supported each other.
 * Yuko Kitajima: Yuko is mistaken by Sougo as his first love from when he was still in elementary school. Despite this, Yuko's shown to have a soft spot to him. she affectionately calls him a cute boy, tending his wounds and pinching his chin as a gesture. Sougo also don't mind shielding her from enemies attack, even after knowing her identity as Another Kiva. It is shown that Both of them develop a romantic relationship, to the point of Yuko indirectly propose Sougo to marry her. Although Sougo later learns that Yuko is not his first love, he still hesitant to attack her. Upon Yuko demise by the hand of Ora, Sougo grieves over her dead body, showing that despite their short-lived relationship, he grows fond of her.

Future Kamen Riders:

 * Rentaro Kagura: He met Sougo in a dream and helped him choose his own future and resist Sworz.
 * Mondo Douan: Sougo defended and saved him from Geiz, but later it turned out that the power of Quiz is needed for the Ridewatches.
 * Rento Makina: Sougo develops a good friendship with Rento as the latter saves him from Humanoise as Kikai. Sougo was also horrified as Kikai was unwillingly brainwashed to kill him. After Sougo undoes Rento’s reprogramming, Rento thanked him.
 * Kamen Rider Ginga:

Portrayal
Sougo Tokiwa is portrayed by So Okuno (奥野 壮). As Kamen Rider Zi-O, his suit actor is Seiji Takaiwa (高岩 成二).

Rider No.
As the leading rider protagonist of Kamen Rider Zi-O, Zi-O is labelled Kamen Rider #35 (仮面ライダー35号) and Heisei Rider #20 (平成ライダー20号).

Etymology
Sougo Tokiwa's name is play on, the place where Shotaro Ishinomori lived and started his manga career during 1956 to 1961. "Tokiwa" also carries the word Toki (とき), which can be translated into time when it is written in kanji "時".

"Zi" in Zi-O's name could mean either time (時) or character (字), representing his "watch" and "Katakana" motifs while the "O" means king (王). It may also be for the number 20 (2 - Ji, 0 - Ō), referencing that Zi-O is the 20th Heisei Rider.