Sougo Tokiwa/Previous Timeline

Sougo Tokiwa (常磐ソウゴ) was the Demon King (魔王) and ruled the world in 2068 as Ohma Zi-O (オーマジオウ), alternatively spelled Oma Zi-O.

Rise Of the Demon King
When the timeline was in its initial position, Sougo Tokiwa obtained the Zi-O Ridewatch II and gaining several more abilities to manipulate time as he wishes. Afterwards, he evolved into Kamen Rider Ohma Zi-O from his base form on the event of Oma's Day and began his rule over the Earth.

Because of disruptions in the timeline caused by various elements, including his own youthful self, Sougo's evolution into Ohma Zi-O was delayed. During his final battle against Swartz, the loss of his comrades caused him to finally become Ohma Zi-O using the Ohma Zi-O Driver and destroy Swartz. After his victory, Sougo chose to rule the world, ending up into the formation of military rule.

Zi-O's Arbitrary Rule
At the start of the series, Tsukuyomi and Geiz, along with the Resistance, attempted to wage a war against Sougo, only for him to effortlessly destroy them, before declaring that none of them were capable of defeating him because he was "born to be king". Some time after this, Tsukuyomi and Geiz traveled to the past, with one intent on changing Sougo's fate of becoming Ohma Zi-O and the other wanting to kill him before he can embark on the path.

Meeting his younger self
One day, as he was sitting on his chrysanthemum throne in an isolated field, Sougo sensed his younger self's presence, who had been sent to 2068 by Tsukasa Kadoya, and pondered if his youthful self wanted to speak to him. He materialized the Ryuki Ridewatch and summoned Dragreder to bring both his past self and Tsukuyomi to him. As the past Sougo spotted him, but was unsure of his identity, Sougo proposed that they talk about the dream they both had in their youth about the Dai Mazines destroying the city, stating every exact detail right down to the man in black who approached them. As the past Sougo realized that Ohma Zi-O really was him all along, Sougo stood up as the sudare rose, revealing his face to both his past self and Tsukuyomi. Laughing, Sougo asked his younger self why he was shocked, and was surprised to find his youthful self to be in denial of becoming the demon king. The past Sougo continued to protest, but Sougo assured him it's their dream and destiny to become king and save the world, before telling the past Sougo this was their future. When the past Sougo claimed he would become the "kindest and greatest demon king", Sougo laughed and revealed he swore the same thing, and believed that, thanks to perfection, he had actually succeeded. This made the past Sougo enraged, and he decided to defeat him right then and there.

"How nostalgic. So that's how weak I used to be."

- Ohma Zi-O noting Zi-O's strength.

As he watched the past Sougo shove Tsukuyomi aside in anger and transformed into Kamen Rider Zi-O, Sougo laughed as Zi-O executed a Fourze ZureZure Shooting from his Zikan Girade Gun Mode. The attack destroyed the throne, but Sougo emerged unscathed, having transformed into Ohma Zi-O, which shocked the past Zi-O. Ohma Zi-O described the nostalgia of his original Rider form, noting that he "used to be this weak", before countering with a golden shock wave, sending Zi-O flying through the dirt. Approaching Zi-O, Ohma Zi-O assured him that, at some point in his time, he would receive the power of a demon king, but Zi-O dismissed it, transforming into Kamen Rider Zi-O Decade Armor, and performed a Kuuga Dual Time Break Rider Slash with the Ride HeiSaber. Pulling out the Kuuga Ridewatch of his own, Ohma Zi-O cancelled Zi-O's attack and countered with Kuuga Rider Kick, sending Zi-O knocking Zi-O down on the ground. Ohma Zi-O told his younger self that his indomitable will and refusal to surrender is a quality of a king, but Zi-O told him to shut up and executed a Kiva Dual Time Break, which was countered by Ohma Zi-O's Kiva-based dark energy bats summoned via Kiva Ridewatch, reducing Zi-O to his knees. Refusing to accept defeat, Zi-O attempted to attack his future self again with a Ryuki Dual Time Break Rider Slash, but Ohma Zi-O used his own Ryuki Ridewatch to summon Dragreder and made the dragon attack Zi-O, knocking him back down to the ground once more. Tsukuyomi came to the young Sougo's aid, and Zi-O had become thoroughly overwhelmed by his future self's power. However, Ohma Zi-O offered him a choice: if the past Zi-O did not wish to accept his fate as a malicious demon king, he must destroy his Ziku-Driver.

Zi-O pondered over this choice, not really wanting to give up his power. Ohma Zi-O generated golden energy from his clock hand-style cape and launched it at Zi-O, drawing the rider closer before detonating it and forcing the past Sougo out of his transformation. He then created a small time window to reveal that Kasshin was overpowering Kamen Rider Geiz Faiz Armor, at the same time stating it would not be long before Geiz was killed. Telling the past Sougo to return to 2018, Ohma Zi-O created a time portal and allowed both his past self and Tsukuyomi to pass through it and return to the present. Closing the portal, he expressed his interest in the decision his past self would make. Cancelling his transformation, before sitting back on his repaired throne, Sougo sensed his past self letting Geiz destroy his Ziku-Driver, and laughed as he was erased from the timeline. After the past Sougo, despite knowing the horror of becoming the demon king, became Kamen Rider Zi-O again, Sougo was restored back to existence in the timeline, laughing as he knew his past self couldn't give up his dream.

Message from the Future
"There are six powers left for you to obtain. Obtaining all the Watches is... your path towards kingship. The path to conquest!"

- Ohma Zi-O presenting his past self the final Ridewatches to become the Demon King. After the past Sougo acquired the power of Trinity and the Blade Ridewatch, Daiki Kaito presented Sougo and Geiz with a message from Ohma Zi-O, who congratulated his past self for having collected the Blade Ridewatch, having known about it all along. Ohma Zi-O then manifested six Ridewatches: Agito, Hibiki, Kabuto, Den-O, Kiva, and Drive, and told the past Sougo that he would have to obtain kingship by acquiring the remaining six Rider powers.

Duel of the Demon Kings & Time Alteration
"My youthful self." "Ohma Zi-O." "So you've obtained the power of all the Riders. Regardless, you're still no match for me." "Let's see. I've got a feeling this is going to work out."

- Ohma Zi-O challenging GrandZi-O to test his new power. After his past self obtained the GrandZi-O Ridewatch and defeated Another Den-O, Ohma Zi-O teleported Sougo back to 2068, and forced him in his GrandZi-O form. Standing in front of GrandZi-O, Ohma Zi-O congratulated his past self for having successfully obtained all of the Rider powers, but claimed he's still no match for him. GrandZi-O, believing he can fare against his future self, challenged Ohma Zi-O. He accepted the challenge and told him to come face his future self as he manifested two Rouze Cards and Double's cyclone energy attacks, which GrandZi-O deflected as he ran towards Ohma Zi-O. Face to face, Ohma Zi-O traded punches with GrandZi-O before both riders forced one another back and summoned manifestations of Kamen Riders Kuuga and Build. As the manifestations fought, Ohma Zi-O teleported in front of GrandZi-O and resumed their battle, blocking every one of GrandZi-O's attacks with no effort. Despite GrandZi-O's proclamation to end his tyrannic rule after Kuuga and Build's manifestations dissipated, Ohma Zi-O reminded him they were still the very same Sougo Tokiwa and scolded his past self for not acknowledging his destiny. This angered GrandZi-O as he summoned a manifestation of Drive. Ohma Zi-O took control of the manifestation and corrupted it, forcing it to attack GrandZi-O and defeat him with a Full Throttle Rider Kick, cancelling the past Sougo's transformation.

As Woz teleported and rushed to the past Sougo's side, who wondered why he lost, Ohma Zi-O revealed to him he hadn't truly acquired all of the Riders' powers, as the past Sougo's Drive Ridewatch was the one Geiz had stolen from Ohma Zi-O before. As the past Sougo refused to submit, Ohma Zi-O berated his stupidity and fired a shockwave at his past incarnate, forcing Woz to send the past Sougo back to 2019. Now alone, Sougo commended Woz for his action, but the Drive manifestation dissipated and chronal energy surged through 2068. Sougo realized that someone in the past had altered the timeline, placing his current one in jeopardy if the new one cemented in history. Eventually, his past self was able to return the timeline back to normal, and Ohma Zi-O's existence was untouched.

Aiding Younger Self against Barlckxs
During the Quartzer crisis, he summoned his past self to his era and motivated him to defeat Barlckxs, also revealing that Ohma Zi-O is still the 19-year-old Sougo's future, not SOUGO's. He later provided his past self with another step towards the ultimate power: the Ohma Zi-O Ridewatch. This eventually allowed young Sougo to defeat SOUGO.

Zi-O's Final Challenge
"Tell me. What is Ohma Zi-O's power?" "The power to destroy time. Someone like Swartz does not have the power to destroy the world. He plans to have you destroy the dimensions." "But I won't become you." "Oh, really? You are me. I look forward to seeing... which timeline you destroy, and how you go on about it."

- Ohma Zi-O explaining his power to the past Sougo. After Hiryu Kakogawa's alternate timeline was erased, Ohma Zi-O's existence was reestablished in history. Attacking the Resistance, Sougo forced them into a corner until the past Sougo arrived and transformed into Kamen Rider Zi-O. Relocating to a new field, Ohma Zi-O stated he had no recollection of his past self's returning to 2068 a second time, which Zi-O assured that history has changed, and what was Ohma Zi-O's past was Zi-O's future. Accepting this new event, Ohma Zi-O told Zi-O it's pointless to change their history, but Zi-O disagreed and fired his Zikan Girade gun mode at Ohma Zi-O, which he deflected with his power. He later blocked Zi-O's sword strikes with his arm before seizing his weapon and unleashing an energy wave at Zi-O.

As Zi-O rose, Ohma Zi-O saw him transform into Zi-OTrinity and charge at him with the Saikyo Zikan Girade, blocking every strike from the giant blade and even the King Giri Giri Slash. Zi-OTrinity rushed forward and attacked with the Saikyo Zikan Girade with all his might, which Ohma Zi-O countered with his own strength, causing a fallout explosion under the Demon King's feet. In a standoff, Ohma Zi-O was shocked to see Zi-OTrinity push his arms up and place the sword's tip at his torso, executing a Trinity Time Break Burst Explosion that sent Ohma Zi-O crashing into a mountain. Falling down to the ground, a staggering Ohma Zi-O admitted he never had that kind of power in his own youth. Zi-OTrinity said his power was not just his own but his comrades' as well, something Ohma Zi-O never had. Finding Zi-OTrinity's claim amusing, Ohma Zi-O surmised that his past self would also have to sacrifice himself for his friends as well, forcing the past Sougo to cancel his transformation and send both the shocked Geiz and Woz back to 2019.

Ohma Zi-O then realized the past Sougo did not want his friends to find out about his planned sacrifice, as he also admitted that fighting each other was meaningless. He also surmised Ohma Zi-O never had any intention of killing him, as they were the same person. Hearing the past Sougo's demand to know what his power is, Ohma Zi-O revealed it was the power to destroy the very fabric of time and space, and that Swartz was using their power to enact that, since the Time Jacker could not do it himself. As his past self still claimed he would not become him, Ohma Zi-O assured him otherwise, and questioned what choices he would make, before sending him back to 2019.

Against his own judgement, Sougo chose to help his past incarnate, and raised his hand and transferred some of his power into a blank Ridewatch Tsukuyomi had in her pocket, which Sougo's youthful self had previously slipped into hers as he saved her from Ohma Zi-O's attack earlier. This created the Tsukuyomi Ridewatch for her to use in 2019.

Swartz's Defeat & Ohma Zi-O's Finale
After his past incarnate defeated Swartz with the power of Ohma Zi-O and planned to erase the current timeline, Sougo asked his youthful self if that was his decision as they conversed one last time. Sougo told him they had the right to be king for having saved the world, but the past Sougo claimed the world was saved by Geiz's and Tsukuyomi's sacrifices and the power of the past Kamen Riders, and there's no point in ruling without his friends with him. Realizing that his past self had chosen a virtuous path instead of a ruler's, Sougo assured him the power of Ohma Zi-O was both destruction and creation, which cemented the past Sougo's resolve to destroy the timeline and create a new one, effectively rewriting history. Before his past self left, Sougo told him he would never have another chance to become king. His youthful self's only response was that he would, albeit through a different way as the future was always in flux and unpredictable. Laughing in amusement, Sougo bade farewell to his past self before being erased permanently from the timeline, claiming that it was interesting to have met his youthful self.

Personality
From what was known about him, Ohma Zi-O was shown to be very arrogant due to his tremendous power, proclaiming that he was chosen to be the ruler of the world from birth. He did not even view the resistance fighters as serious threats. His arrogance was not without merit, however, as his battle against his younger self demonstrated impressive mastery over his abilities of his predecessors. Furthermore, he was extremely confident and fearless, as he openly suggested to his past self to throw away the Ziku-Driver, an action that would result in his own temporal erasure, and even arrogantly laughed as he was disappearing from the timeline, suggesting that everything young Sougo would do were within his calculation and expectation.

However, he still believed that his tyranny had somehow saved the world. When young Sougo claimed that he wished to become the "kindest and greatest" Demon King, this Sougo replied that he did in fact become the "kindest and greatest" Demon King, albeit not in the sense of kindness, but in the sense of perfection.

Although known for being a villainous demon king, Sougo was still shown to have retained some of his past traits. He continued to encourage his younger counterpart to the path to kingship, although it was mostly for saving his own existence. During the Quartzer crisis, he dragged his past self to his era and motivated him to defeat Barlckxs and provided him with another step towards the ultimate power: the Ohma Zi-O Ridewatch. He was also quite amused when he found out that Zi-OTrinity could briefly overpower him. He then explained the true extent of his power and gave some of his power to Tsukuyomi (albeit against his will), resulting in the creation of the Tsukuyomi Ridewatch.

In the series finale, it was revealed that Ohma Zi-O was in fact the previous version of Sougo, who abused his powers and instead turned it into a totalitarian future. When Sougo himself revealed that he was going to use the powers to reset time instead, Sougo did not get upset, but rather became amused and looked forward to seeing a future that the past Sougo would create without the powers of Ohma Zi-O. Even when knowing full well that he would permanently cease to exist, Sougo harbored no ill will towards his youthful self's actions, and he willingly let himself be erased without resistance, this time with a satisfying laugh of amusement and consent.

Powers & Abilities

 * Disintegration: Ohma Zi-O can send out a powerful wave of energy that can disintegrate anything in its path.
 * Enhanced Awareness: Ohma Zi-O immediately sensed and identified the threat of incoming missiles.
 * Velocity Manipulation: Ohma Zi-O can freeze dozens of missiles.
 * Time Manipulation: Ohma Zi-O can freeze time before disintegrating enemies. According to Tsukuyomi, Ohma Zi-O has all of the abilities that come with Sougo Tokiwa's Zi-O II Ridewatch, thus implying that Ohma Zi-O can reverse time as well.
 * Timeline Alteration: Tsukuyomi theorizes that Sougo's dreaming ability causes his encounters with the future Riders to actually happen in reality, an ability that (according to her) Ohma Zi-O also seems to possess.
 * Telekinesis: When an army of Time Mazines attempt to crush Ohma Zi-O, he simply uses telekinesis to hurl them into each other.
 * Time Portal Creation: Ohma Zi-O can create time portals, which are even capable of forcefully pulling a person into themselves.
 * Keen Manipulator: Like his past iteration, the future Sougo is also manipulative, even towards his younger self.
 * Legend Riders' Powers: Ohma Zi-O has the powers of all the Riders prior to the year 2068. He can tap into their powers by activating their Ridewatches as well as simply through his will. He can also summon Rider clones and even corrupt the ones summoned by others.
 * Kuuga: Summons an energy construct of Linto Hieroglyphics to create an energy kick.
 * Kiva: Summons a colony of energy bats.
 * Ryuki: Summons Dragreder to attack his target.
 * Blade: Summons two large Rouze Cards to attack his target.
 * Double: Summons a green/purple colored energy cyclone.

Weaknesses

 * Sougo Tokiwa: Because Ohma Zi-O is Sougo's future self, any disturbance in the timeline (for example, the Ziku-Driver's destruction or Sougo's death) can erase Ohma Zi-O's existence.   It is also revealed that Ohma Zi-O does not have any intention to go all out against his younger self for this very reason, a fact acknowledged by young Sougo himself after the third and final match.
 * Lack Of Companionship: In the final match against his younger counterpart, Ohma Zi-O was left overwhelmed by Kamen Rider Zi-OTrinity, due to him not having the power of companions alongside him. This allowed his younger counterpart to briefly overpower him to his knees, although he was probably trying his best not to kill his younger self.
 * Hiryu Kakogawa (formerly): Another Zi-O II's ability to alter history and reality can put Ohma Zi-O's existence in jeopardy.

Equipment

 * Ohma Zi-O Driver - Transformation device. Ohma Zi-O possesses a gold-colored upgraded variant of the Ziku-Driver.
 * Ridewatch Holder - Ohma Zi-O possesses a gold-colored variant of this. However, he never uses it.
 * Ridewatches - Transformation trinkets. He was in possession of at least the Ghost and Drive Ridewatches before being stolen by Geiz. He currently is seen to be in possession of the Kuuga, Kiva, Ryuki, Blade, and Double Ridewatches (of his time), but might have other ones as well.
 * Dragreder - Ryuki's Contract Monster, summoned through the Ryuki Ridewatch.

Portrayal
As Sougo is an old man at this point in time, he is voiced by Rikiya Koyama (小山 力也), who also voiced the Ziku-Driver. His civilian silhouette is portrayed by Seiji Takaiwa (高岩 成二) , while retaining Rikiya's voice. His suit actor as Ohma Zi-O is Yasuhiko Imai (今井 靖彦).

Etymology
The "Ohma" in his name refers to (逢魔時) in Japanese mythology and also a reversed spelling of Demon King (魔王(マオー)).