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 inspired to become a great king through kindness by becoming Kamen Rider Zi-O (仮面ライダージオウ). However he learns from Tsukuyomi and Black Woz that in 50 years time, he is destined to become the tyrannical ruler of their time, Ohma Zi-O. To this end, Geiz Myokoin was 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 a 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 was unknowingly rescued by his original counterpart, who from an unseeable distance, summoned a series of pink katakana that stopped time, allowing the young Sougo to save Hiryu 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, Ohma Zi-O. Just before Sougo could reply, a fight occurs and Tsukuyomi decide to test whether Sougo is really Ohma 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 Girade 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 Ohma 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 version 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 from 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 intervened 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 took 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.

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 Ohma 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.

The Fated Meeting Between Old and Young
Sougo awakens on a dystopian land 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 Ohma Zi-O. The two are then transported by Dragreder to the presence of Ohma 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 Ohma Zi-O. Ohma Zi-O laughs in nostalgia, having not seen his default form for over 50 years, and attacks the young boy. Ohma 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 Ohma Zi-O with a Kuuga attack from his Ride HeiSaber, but Ohma Zi-O whips out the Kuuga Ridewatch and counters it, sending it back to Sougo. Sougo gets up and readies a Kiva attack, while Ohma 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. Ohma Zi-O then tells Sougo that there is one thing he can do to prevent the world’s 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
After being traumatized by his encounter with his future self (as Ohma 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 Ohma Zi-O. Eventually, Geiz convinced him that he could still change his fate, despite the risk of Ohma 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.

Meeting White Woz and Shinobi
One morning as Sougo fell asleep, he dreamt of a Kamen Rider named Rentaro Kagura, a ninja from the year 2022 who became Kamen Rider Shinobi. However unbeknownst to him, this dream actually materialized Rentaro Kagura to the real world where Rentaro later became Another Shinobi. As Another Shinobi began to wreak havoc in the city, Sougo and his team head out to investigate and eventually encounter it. Partway through, they encounter an White Woz, who antagonizes Zi-O and Black Woz and is completely loyal to Geiz, calling him "GeizRevive". After defeating Another Shinobi for them, he reveals that because Sougo temporarily gave his powers up, it created a new timeline where Ohma Zi-O did not exist, and from there came him.

When the team returns to 9 5 DO, they discuss how White Woz were able to control their actions using his Future Note, which was a problem. Deciding to just focus on Another Shinobi, Sougo decides to go confront Rentaro himself (unknowingly following White Woz's Future Note), an action that was quickly dis-advised by Black Woz, who told Sougo doing so would jeopardize his existence and his future. Sougo went anyway, telling Black Woz that he believed that Rentaro was a good man and could eventually become Kamen Rider Shinobi in the future. Sougo meets with Rentaro and encourages him to believe in his future self, later Rentaro affirming such belief after being defeated several times. However White Woz appears and creates the Shinobi Miridewatch, using it to defeat Another Shinobi as Woz Futurering Shinobi. Even though Sougo failed to protect Rentaro, he still held a strong belief that Rentaro will rediscover that power again in the future.

Meeting the Puzzle Master, and the Quiz Miridewatch
Sougo and Geiz head out to investigate an attack instigated by an Another Quiz, who was attacking people at a science laboratory. The two transform to fight the Another Rider, but are suddenly told stop fighting it by Mondo Douan, who just arrived and wanted to defeat Another Quiz for himself. The two refuse, and Mondo transforms into Kamen Rider Quiz, eventually targeting both Zi-O and Geiz as his enemies and defeating them both as well. As they watch Quiz approach Another Quiz, Ora appears, stops time, and retreats with Another Quiz. After time resumes, Quiz chases after them. Black Woz appears and tells the team that Quiz is most likely from GeizRevive's timeline. They also become confused as to why Quiz was able to coexist alongside his Another Rider counterpart.

The Mirror World, Accepting Fate, and Zi-O II
"Heads and tails... The past and the future... Light and darkness... A Watch that rules over the two worlds!"

- Sougo, after creating the Zi-O II Ridewatch

Following the Another Quiz incident, Sougo and Geiz finds themselves pursuing the elusive Another Rider, Another Ryuga, whose reflection powers continually frustrated for the Kamen Riders. After numerous encounters, the group discovered this Another Rider 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 the nature of 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 the monster. 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 advice 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 Ohma 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 Zi-O Ridewatch II as Mirror Sougo merges with him and unlocks the power to reverse time. Using this newfound power, Sougo saves Geiz before transforming into Zi-O II and defeating Another Ryuga.

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

Unravelling the past and GeizRevive's confrontation
To be added.

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

Meeting Agito
To be added.

The Disciple of Hibiki
To be added.

First Love, Ginga, and Kiva' Powers
To be added.

The ZECT Riders and Tsukuyomi's Past
To be added.

The Ridewatch of Imagin, Zeronos And Achieving GrandZi-O
To be added.

New Time, Another Zi-O II
To be added.

Aqua's Arrival and Another World
To be added.

Krim Steinbelt and Conflict with the Quartzers
To be added.

Vanishing Ridewatches and Foes from Past
To be added

Final Battle and Time Reset
Sougo shares a meal with his uncle Junichiro before going into the final battle. After the meal, Junichiro reveals that he has fixed all the Ridewatches. Sougo, taking the Watches, goes to war for the last time.

Just as Another Decade is about to finish off Decade, Woz, Geiz and Diend, Sougo uses his power to stop him from doing so. He proudly proclaims to the Time Jacker that no matter how Swartz tampers with history, Kamen Riders will always exist. He transforms into GrandZi-O and fight Another Decade.

"Woz... Rejoice. Rejoice to me."

- Sougo orders Woz to announce his rejoice in anger

Zi-O initially gains the upper hand as he summons OOO Tajadol Combo, Gaim Pine Arms, Double Xtreme and Wizard Infinity Style to overpower Another Decade. However, Swartz evens the odds by summoning villains from previous series: Evolto, Daguva, Sagittarius Zodiarts, Utopia Dopant and Gamedeus. The villains defeat Sougo's Riders, and Another Decade, along with them, fires a concentrated energy blast at Sougo, knocking him out of the transformation. Before Swartz can end Sougo's life, Geiz steps in and shields Sougo from Swartz's energy blast, sacrificing himself for Sougo. Geiz, in his dying breath, tells Sougo to become Ohma Zi-O, saying that he believes the latter can become the "greatest", "kindest" demon king like he originally intends to. The death of his friend makes Sougo enraged, and his Ziku Driver turns into Ohma Zi-O's golden Ziku-Driver.

"It's not like someone like you can grasp the scope of my powers. This power of mine...is the power of ALL the Kamen Riders"

- Sougo to Swartz after the latter fails to absorb his power

Sougo transforms with the new belt into Ohma Zi-O. He coldly commands Woz to rejoice him, which the latter does. Swartz is ecstatic, wanting to claim his power, and immediately does so by absorbing it. However, Ohma Zi-O's power is too much for the Time Jacker to handle, and the apsorption backfires as a result. Sougo boasts that Swartz cannot comprehend the scope of Ohma Zi-O's power, as his power is the power of literally all Kamen Riders known to exist. He then effortlessly destroys the villains and some other kaijins with a single strike each. Swartz, realizing Ohma Zi-O is out of his league, attempts to make a getaway to his timeline. Just as the Time Jacker is summoning a Dimensionall Wall to escape, Kamen Rider Tsukuyomi stabs him from behind. Enraged, Another Decade fires an energy blast at her, killing her. This makes Sougo even more furious, and he aims a Rider Kick at Another Decade. Swartz also prepares a Rider Punch to counter him, but ultimately falls before the sheer might of Ohma Zi-O's power. The Rider Kick finally lands, and Another Decade is destroyed, and a surge of temporal energy sweeps through the area, making the other monsters vanish, ending the Time Jacker's scheme for good.

After the battle, Woz kneels before Sougo, content that the world is finally saved, and that Sougo is going to rule it from then on. Nevertheless, he replies that it is not going to happen that way, because he will destroy this timeline. Suddenly, Sougo's future self's voice echoes, asking his youthful self whether he has made a decision. Young Sougo is then drawn into a meeting with his future self in the latter's throne room.

Future Sougo states that after saving the word, young Sougo has the right to become King and rule it as he wishes. Young Sougo replies that he is not the one who saves the world, but rather, Geiz, Tsukuyomi, and the power of all Kamen Riders, and that he cannot bear to live within a world where he alone reigns supreme without his friends. Future Sougo tells him that destruction cannot come without creation. His younger self agrees, and proclaims he will use Ohma Zi-O's power for creation and rewrite the world's history. Future Sougo notes he will never be able to return to the throne if he rewrites history. Nevertheless, young Sougo determines that he can achieve that goal. This amuses future Sougo, who admits that meeting his youthful self is interesting for him. Future Sougo is then erased from the timeline, as the young Sougo proceeds to rewrite history.

After resetting the timeline, Sougo finds himself in September 2018. He has breakfast with Junichiro before going to school. In this new timeline, the people involved in the original events are shown to be alive and well, as well as being on the good side and with no memory of the original events. Geiz and Tsukuyomi become Sougo's classmates, along with Heure and Ora. Ora notes that they are about to be late for school, prompting everyone to rush.

Woz, who remembers the events of the old timeline, quietly notes to himself that his Ohma Advent Calendar will have a different story to tell as he watches the Sougo Tokiwa and his friends rush to school in joy.

Ohma Zi-O's Timeline
On the day known as Oma's Day, Sougo Tokiwa transformed into Ohma Zi-O and used seven giant monstrous machines called Dai Mazines to destroy the world and become the revered "Demon King".

After his past self and Tsukuyomi arrive in 2068, Ohma Zi-O, reveals himself to be the person he had feared to be and the past Sougo tries to destroy him, to no avail. Ohma Zi-O then tells Sougo that there is one thing he can do to prevent the world’s 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. This resulted him being briefly erased from the timeline after his past self let Geiz destroy his Ziku-Driver, but was restored thereafter knowing his past self couldn't give up his dream.

Even after Oma's Day passed, Ohma Zi-O is still intact in the timeline, which meant that Sougo was still on track to become Ohma Zi-O sometime in the future. Ohma Zi-O reveals that there are six remaining Ridewatches left to unlock. After his past self managed to obtain the power of GrandZi-O, he made his way to 2068 in order to face off against Ohma Zi-O once again, only to be be a futile effort due to the past Sougo still yet to collect the last remaining power.

When the past Sougo traveled back to 2068 to face off with Ohma Zi-O one last time, Sougo managed to push past Ohma Zi-O down to his knees. Sougo explained to the Demon King his victory is due to him fighting alongside his companions, something that Ohma Zi-O lacks. Ohma Zi-O tells his past counterpart the power of Ohma Zi-O is the only power left to defeat Swartz before sending him back to 2019, before helping create the Tsukuyomi Ridewatch.

Eventually, his past self accepted his fate, inevitably transforming into Ohma Zi-O and defeated Swartz. Despite the older Sougo suprised that his younger self's wish to create rather than destroy, he was amused with his past self's desision. Ohma Zi-O bade farewell to his past self before being erased permanently from the timeline, claiming that it was interesting to have met his youthful self.

GeizRevive's Timeline
In this timeline, Geiz defeated Ohma Zi-O and became known as the world's savior, later evolving into GeizRevive, creating a peaceful timeline and according to White Woz, "like time itself has stopped". This timeline is likely erased after the fated duel between Zi-O and Geiz that took place in Oma's Day was averted.

It is never explicitly stated whether Sougo was alive or not in this timeline.

Prophesied Vision
In a version of Oma's Day, seen by Sougo through the use of the Zi-O Ridewatch II, he sees a future of a fated duel between Zi-O II and Geiz to declare which future will be secured. While the dream did not reveal the outcome of the fated battle, it was likely erased after Oma's Day had passed and such battle didn't happen.

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.

Personality
Sougo is described as an ambitious young man with a strong desire to be king. 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 a lot of 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 closest friends he ever had. Sougo 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.

His views for kingship changed once he discovered the existence of his tyranical alternate future self, and temporarily abandoned his quest for kingship. However with support from Geiz, Sougo began displaying emotional and psychological resilience when facing such moral dilemmas; even when confronted by the Mirror World manifestation of his own dark side, Sougo persevered and adapted, and 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. Despite so, Sougo is still someone who is sensitive towards people who tell him that he will or recommend that he become an evil demon king, despite him on several occasions voicing out his intentions to become the very opposite.

Sougo is a peaceful and genuinely kind man at heart who confidently feels obligated to show compassion and empathy even towards people who have committed horrible deeds, such as Yuko Kitajima, Heure, and Ora, as he feels it is a quality that kings should possess. 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 showed an inability to come out with his feelings, hiding the fact that he genuinely felt lonely after Geiz and Tsukuyomi left and continued insisting he was fine. It wasn't until Junichiro built up the courage to actually scold him over this, advising him to just come out with his feelings. This encouraged Sougo to admit his loneliness to both Geiz and Tsukuyomi and asked them to return to 9 5 DO.

Despite his peaceful nature, it doesn't mean that Sougo never shows anger. The first example was right after he discovered the result of the future he caused and witnessed the man he feared to become, and attacked Ohma Zi-O to no avail. After Heure was killed by Ora, and his death was mocked by Another Drive, it left Sougo in a rage and he mercilessly attacked and killed Another Drive. Following Swartz informing of three impossible choices to stop him, Sougo couldn't do anything but scream Swartz's name in grief and anger. That anger and rage took a turn for the worse after Geiz's death, who shielded him from Another Decade's attack. Combined with Tsukuyomi's supposed betrayal and the fact his life was manipulated by Swartz this whole time, Sougo then accepted the power of Ohma Zi-O and defeated Swartz with no hesitation. Despite his transformation into Ohma Zi-O, Sougo was able to not let his grief corrupt him, leading him to not go on the path of villainy like his future self did, but instead restore the multiverse back to normal.

Throughout the course of his journey, Sougo has improved his combat skills considerably, rising from the ranks of an amateur combatant to a formidable warrior, who could contend with more seasoned warriors such as Geiz in a relatively short period of time. In regards to his fighting habits, Sougo is a resourceful and competent fighter who relies heavily upon his huge arsenal of Rider Armors and weapons. While not a fully technical fighter, Sougo approaches a fight in a composed manner and remains calm and level-headed under fire. He is a focused and cunning strategist who can adapt to most situations with innovative strategies.

Because of his optimistic approaches, Sougo adds the verbal tic "Feels like it" (気がする) at the end of most of his sentences.

Legend Rider Catchphrases
Occasionally when Sougo dons a new RiderArmor, he will say the original Rider's catchphrase, albeit somewhat altered:
 * Build: The rules of victory have been set! (Sougo moves his hand back and forth after finishing, annoying Sento)
 * Ex-Aid: With no continues, I feel like I can clear this game! (Sougo adds his verbal tic in)
 * Ghost: I'm gonna try letting my life burn bright! (the original phrase is My life is burning bright)
 * Gaim: Hanamichi, on Parade! (the original phrase is Hanamichi on stage)
 * Fourze: I'm going to Space! (In the original script, Sougo adds a Wa (は), which changes the original meaning of the phrase.)
 * OOO: Seiya! (Sougo only says this at the end of Scanning Time Break)
 * Double: Now, tell me your sins! (the original phrase is Now, count up your sins)

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.
 * Temporal Freezing: Through currently unknown means, Sougo Tokiwa once shared the Time Jackers' ability to freeze time. The only known usage of this ability when he was eight, summoning a series of pink katakana that slowed down time, saving Hiryu Kakogawa from the falling debris. It is currently unknown if he still has this ability.
 * Timeline Protection/Manipulation: Upon acquiring the Zi-O Ridewatch II, Sougo 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 Ohma Zi-O has these abilities as well, which were what made him so fearsome.
 * Temporal Rewind: Sougo can reverse time, allowing him to redo a certain event and change the future, however he must have had to personally witnessed the event in order to do so. 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. However, Sougo stopped rewinding time once aware of how dangerous these abilities pose to his friends.
 * 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. The third time was when he dreamt of Aruto Hiden in the year 2019 during the events of Kamen Rider Zi-O: Over Quartzer, though it did not give rise to an Another Zero-One during the present day.
 * 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.
 * Teleportation: Sougo as GrandZi-O has ability to teleport himself, which is helpful to him as defense against several attacks. This ability seems to be unable to be traced by Zi-O II's future sight.
 * Telekinesis: When an army of Kasshins tried to crush Zi-O's Ohma Form, he simply used telekinesis to hurl them into a wall.

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'. However,  Sougo does manage to pass his exams with an 82/100 and avoid dropping out. Despite having snored through his actual studying, Sougo is able to graduate.
 * Poor Gaming Skills: When Sougo plays Mighty Action X, he fails several times and this is indicated when he uses Kamen Rider Ex-Aid based attacks with his Ride HeiSaber and his Critical Time Break finisher with Ex-AidArmor, failing to land a perfect on any of those attacks hence making Sougo weak in using powers of any of the Gamer Riders' powers.
 * Future Sight Exploitation: Zi-O II's future sight can be exploited by opponents moving super-speed by attacking him fast enough to stop him from counterattacking on time, such as GeizRevive Shippu and Kamen Rider PunchHopper. Currently this has only been done by Geiz, since Zi-O II had managed to counter PunchHopper.
 * 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.
 * Kamen Rider Drive (Formerly): GrandZi-O could not completely control Drive's powers at full capacity due to him not having faithfully acquired the Drive Ridewatch through his usual means, and was easily countered by Ohma Zi-O. During the events Kamen Rider Zi-O: Over Quartzer, Sougo formally received it from Krim Steinbelt, and was able to take full control of Drive's powers.

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.

Kamen Rider Zi-O's ending theme is entitled "Zi-O, Toki no Ōja".

Devices

 * Ziku-Driver - Transformation device
 * Ohma Zi-O Driver - Gold-colored upgrade variant of the Ziku-Driver
 * 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, Zi-OTrinity's and GrandZi-O'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.

Legend Riders' weapons used by Zi-O DecadeArmor and GrandZi-O:

Vehicles

 * Ride Striker
 * Time Mazine

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), who has been the leading suit actor for the majority of the main Heisei Riders (minus Kuuga and Hibiki). Zi-O is Takaiwa's final suit acting role for main Rider.

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.