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This "interesting drama" of Hiden Intelligence's destruction... It's all going according to my scenario. Right at 100 percent. No, 1000 percent.
~ Gai remarking to Yua on his plan to destroy Hiden Intelligence.
Gai: As the Ark guides us, we approach a new age in our mythology.
Yua: Mythology?
Gai: Yes. The mythology of the Kamen Riders.
~ Gai conversing with Yua on the age of the Kamen Riders.
When the five horns cross, the golden soldier Thouser is born!

Presented by Zaia.
~ Kamen Rider Thouser transformation announcement.

Gai Amatsu is the CEO of Zaia Enterprise Japan and the main antagonist of Kamen Rider Zero-One.

He is Yua Yaiba's superior and the benefactor of A.I.M.S. Secretly, he is the one who caused the Ark satellite to deem humanity as a threat to the world by feeding it knowledge about humanity's atrocities, leading to the Daybreak Town Incident and the creation of MetsubouJinrai.NET. He seeks to have Zaia Enterprise take over Hiden Intelligence by inciting panic over HumaGears to lower Hiden's stock.

By inserting both a Progrise and ZetsumeRise Key into the Zaia ThousanDriver, Gai transforms into Kamen Rider Thouser.

He is portrayed by Nachi Sakuragi.



Gai was born on October 10, 1974. At some point in his teenage years, Gai attended Stanford University. When he was only 17, Gai created the web body Thousand Network. A year later, Gai would graduate from Stanford and began pursuing his own company. Eventually, in 1996, Gai was hired by Zaia Enterprise and quickly rose through the ranks to become one of the top executives of the company. In 2007, Gai was transferred to Zaia's Japan branch and soon took over as its CEO.

Gai Amatsu soon came to idolize the CEO of Hiden Intelligence, Korenosuke Hiden, believing him to be the one who had what it took to thrust humanity into the future. However, due to their conflicting views on how AI technology should be utilized, Gai and Korenosuke had a falling out and Gai began seeking to surpass Korenosuke's creations.

Zaia Enterprise later collaborated with Hiden Intelligence and a multitude other companies to create the Ark satellite. During this time, Gai fed it information on humanity's propensity for ceaseless war and other acts of violence and destruction perpetrated by humanity, causing the Ark to deem humanity a threat to the world. Because of the conclusion it had reached, the Ark formed MetsubouJinrai.NET and hacked thousands of HumaGears to revolt against humanity in what came to be known as the Daybreak Town Incident. Though the incident was covered up by Hiden as a factory accident, thanks to the HumaGears being contained in a factory explosion caused by Satoshi Sakurai, Gai remained one of the few who knew of the truth behind the events that transpired.

MetsubouJinrai.NET Attacks

Gai first appeared when Yua Yaiba approached him in his office and informed him that she had discovered Hiden Intelligence's secret, that all HumaGears had an auto-data transfer device in them. She also told Gai about how she had discovered that the Progrise Keys thought to have been destroyed in the Daybreak Incident were actually still active, causing Gai to remark that "in other words", the Ark will rise again.

Gai later met with Yua again and instructed her to take down MetsubouJinrai.NET, providing her the Lightning Hornet Key, which he noted had twice the power of Rushing Cheetah, to assist her in the task.

After Yua handed the Mammoth Progrise Key over to Aruto Hiden to assist him in combating the rogue Giger, Gai met with her again and remarked that he did not expect her to hand the key over to Hiden Intelligence. Yua apologized to Gai, but Gai stated that there was no problem and that he would much rather she bring him a new Progrise Key instead as he arranged the Progrise Keys on his table.

After the movie produced by Hiden Intelligence starring a HumaGear actor faced difficulties in production due to attacks from MetsubouJinrai.NET, Yua went to inform Gai of the difficulties in production. However, Gai proclaimed that this "interesting drama of Hiden Intelligence's destruction" was still on track.

Gai later had Yua bring Aruto Hiden, CEO of Hiden Intelligence, to his office so he could meet with him to discuss the sale of Hiden Intelligence to Zaia. Welcoming him to his office, Gai summoned two red couches for them to sit on as he brought Aruto some tea and stated that he would like for him to sell Hiden Intelligence to Zaia. Aruto asked him what he meant by that, but Gai cryptically told him that it was best that he make his decision soon for the sake of his company's future.

After Aruto became Zero-One Shining Hopper and defeated the Dodo Magia Custom 2, Gai observed the battle from a distance, noting that Zero-One was now at 500% past his base power and that he looked forward to his battle with Thouser.

Yua later met with Gai again to ask whether they should keep Fuwa on duty due to his injuries, noting that he could get himself killed. However, Gai stated that they could only watch him and went on to proclaim that the Ark would guide them to a new mythology. As Yua pondered further to what Gai meant by "mythology" Gai stated it was the mythology of the Kamen Riders.

After AIMS's raid to take down MetsubouJinrai.NET was successful and saw the death of Horobi, Yua met with Gai again. Gai remarked that MetsubouJinrai.NET was easier to take down than he expected, though Yua noted that the road to tracking them down was not simple and that the raid saw Isamu Fuwa sacrificing himself to defeat the enemy. Commenting that Fuwa's sacrifice was a commendable act of heroism, Gai got up from his chair and walked towards Yua, declaring that MetsubouJinrai.NET needed to be destroyed in order to prove that Kamen Riders are weapons of the new era. Gai then told Yua that her and the other Riders would forge a new legend. Yua pondered on what Gai said for a moment before noting to him she had heard his orders and heading out.

After Zero-One Shining Assault Hopper deactivated Jin and destroyed MetsubouJinrai.NET's forces, Gai arrived at MetsubouJinrai.NET's base and, trampling over the body of Horobi, retrieved the two new Progrise Keys freshly manufactured by the Ark.

Gai later met with Yua again, who informs him that MetsubouJinrai.NET has been destroyed. However, Gai tells her that MetsubouJinrai.NET will never be destroyed as long as HumaGears exist. Much to the shock of Yua, Gai then reveals himself as the wirepuller behind MetsubouJinrai.NET and as the creator of the Ark and the one who filled it with a desire to exterminate humanity by programming it with knowledge of humanity's atrocities. A shcoked Yua expresses horror at Gai for using both A.I.M.S. and MetsubouJinrai.NET as pawns for his plans when she and Fuwa risked their lives to stop MetsubouJinrai.NET, but Gai calmly tells her that the real battle has not yet begun and that, with Zaia's technology he will dominate the world.

Gai later makes an abrupt appearance at the press conference called by Hiden Intelligence to address recent attacks by ZetsumeRiser-less Magia following the destruction of MetsubouJinrai.NET. At the conference, Gai announces that Zaia Enterprise will be issuing a TOB for Hiden Intelligence and that, once they are in control of the company, they will shut down all the faulty HumaGears. Gai later returns to his office and pulls out the Zaia ThousanDriver from a briefcase, declaring that his plans are running at "1000%".

Rise of Zaia Enterprise

Gai later met with Aruto Hiden to discuss the terms of Hiden's buyout. During the meeting, Gai revealed that the sales of Zaia's latest product, the ZaiaSpec, were doing well but that he hoped to boost their sales even more by staging a competition between Hiden's HumaGears and humans wearing the ZaiaSpec to demonstrate the ZaiaSpec's power. Gai offered to allow Hiden to withdraw from Zaia and hold onto their shares if they win.

The first round of the competition involved floral arrangement and was between Hiden's florist HumaGear model Sakuyo Ichirin and human professional florist Rentaro Tachibana, who was equipped with the ZaiaSpec. The round was administered by Yua Yaiba and presided over by a team of three judges. Rentaro and Sakuyo both prepared bouquets and presented them to the judges, with the judges unanimously choosing Rentaro's design over Sakuyo's. However, Sakuyo protests the decision and calls Rentaro heartless, only for Rentaro to push her over and onto the ground. Through her anger at Rentaro, Sakuyo achieves Singularity, allowing her to be hacked by the Ark and transformed into the Onycho Magia.

As Izu attacks Rentaro, Aruto becomes Zero-One Flying Falcon to deal with the Onycho Magia. Gai transforms into Kamen Rider Thouser to make his debut as the Golden Soldier and pushes Zero-One aside to fight the Magia himself. Thouser quickly destroys the Magia before turning his attention to Zero-One and attacks him to demonstrate Thouser's power. After Thouser overpowers Zero-One in Flying Falcon Zero-One switches to Shining Hopper, but even that is not enough to stand up to Thouser, as Thouser is able to rapidly calculate Shining Hopper's attacks and counter them. After defeating Zero-One and knocking Aruto out of his transformation, Gai declares he has surpassed the Zero-One Driver and Hiden before canceling his transformation. He then reveals to Aruto that he once looked up to his grandfather, Korenosuke Hiden, but that Korenosuke's focus on HumaGears led to him becoming disillusioned with the Hiden CEO before departing.

However, it was later exposed from footage in Sakuyo's backup memory banks that Rentaro had tampered with Sakuyo's floral design in order to win. Not wanting any negative press for the ZaiaSpec, Gai agreed to a do-over of the first round and threatened to sue Rentaro if he didn't comply. Gai later met with Aruto again and revealed that his disagreement with Korenosuke had to do with him believing AI should work alongside humanity, while Gai believed AI should only be used to serve humanity. Gai also revealed that, despite appearing 24, he was actually 45 years old.

During Isamu's confrontation with Yua, Gai showed up and told Fuwa to back away from his employee, transforming into Kamen Rider Thouser to test the ThousanDriver's power against Fuwa as Kamen Rider Vulcan. After beating down Vulcan, Fuwa switched to using Assault Wolf and unleashed a flurry of attacks to beat back Thouser, but Thouser easily wiped them off. Thouser then overpowered and defeated Vulcan Assault Wolf, knocking Fuwa out of his transformation, before departing with Yua.

Gai later attended the do-over round for the Workplace Competition, but the contest had to be put on hold due to Rentaro not showing up. Rentaro eventually stumbled into the room after being brainwashed by a mysterious Hooded Figure and transformed into the Crushing Buffalo Raider. Gai immediately transformed into Thouser to deal with the Raider but Aruto attempted to stop him, saying he could hurt Rentaro. However, Thouser ignored Aruto's concerns and brushed him aside before attacking the Raider. Aruto transformed into Zero-One Assault Hopper and attempted to intervene in the fight, but Thouser overpowered and defeated him before destroying the Raider, releasing Rentaro from the transformation and restoring him to normal. With Rentaro normal again, the first round was able to commence and Zaia claimed victory, though on much more amicable terms this time.



           Kamen rider zero one logo Villains

Ark | Horobi | Jin | Ikazuchi | Little Assassin

Regular: Berotha Magia | Kuehne Magia | Ekal Magia | Neohi Magia | Onycho Magia | Vicarya Magia | Gaeru Magia | Mammoth Magia | Dodo Magia | Arsino Magia
Ark: Ark Magia (Onycho Type) | Ark Magia (Neohi Type) | Ark Magia (Mammoth Type)
Footsoldiers: Trilobite Magia | Dodo Magia Chick

Zaia Enterprise
Gai Amatsu | Yua Yaiba | Giger

Crushing Buffalo Raider | Splashing Whale Raider | Dynamiting Lion Raider | Storming Penguin Raider | Fighting Jackal Raider | Scouting Panda Raider

Kagen | Kasshin | Finis | Will

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