|This article is about a/an Rider in Kamen Rider Zero-One.|
Gai Amatsu (天津 垓 Amatsu Gai) is the 45-year-old former CEO of ZAIA Enterprise Japan. He wished to take over the world using the Ark and manipulated MetsubouJinrai.net from behind the scenes as A.I.M.S.' benefactor, with his company producing much of the agency's technology. After their supposed demise, he became Kamen Rider Thouser (仮面ライダーサウザー Kamen Raidā Sauzā) and bought out Hiden Intelligence following the Workplace Competition, simultaneously becoming its 3rd CEO. However, after the Ark fully revived, he resigned as Hiden's CEO and began aiding Aruto in defeating the Ark. He was later removed as ZAIA Japan's CEO for his repeated failures in regards to the Ark, and was replaced by Williamson Yotagaki.
- 1 History
- 1.1 Early Life
- 1.2 Working with ZAIA
- 1.3 Staying in the Shadows
- 1.4 Nearing Completion
- 1.5 Taking Over Hiden Intelligence
- 1.6 The Golden Soldier Thouser Is Born
- 1.7 The Uncontrollable MetalCluster Hopper
- 1.8 Thouser's First Mistake
- 1.9 The Scorpion's Escape
- 1.10 Exposure
- 1.11 Final Round: The Citizen's Referendum
- 1.12 Obtaining Hiden Intelligence
- 1.13 All for Nothing
- 1.14 Valkyrie's Resignation
- 1.15 ZAIA Japan vs. MetsubouJinrai.net
- 1.16 Reuniting with Thouser and Redemption
- 1.17 Downfall of Gai
- 1.18 Thouser's Department
- 1.19 Final task as ZAIA's president
- 2 Movies and Other Events
- 3 Video Game Appearances
- 4 Personality
- 5 Abilities
- 6 Kamen Rider Thouser
- 7 Equipment
- 8 Family
- 9 Relationships
- 10 Behind the Scenes
- 11 Notes
- 12 Appearances
- 13 References
Gai Amatsu was born on October 10, 1974 and grew up in a strict household. When he was 11, he owned a Dog-Gear named Thouser, created by Hiden Intelligence, but his harsh father, Ikkei Amatsu, was angered by his 99% test score and reluctantly had to return it to secure his education.
Gai was considered a genius prodigy from a young age and graduated from Starford University at the age of 18, with a Master's Degree in Business Administration. While he was a student, he founded the website Thousand Network.
Working with ZAIA
Gai began to work with a multitude of other technological companies to develop Satellite Ark, a special A.I. manager within Daybreak Town. Gai had heavily idolized Korenosuke Hiden, who he believed had what it took to thrust humanity into the future. However their conflicting views on how A.I. technology should be utilized resulted in estrangement and fueled Gai's inner obsession with surpassing Hiden and his Humagears. To do so, he fed the Ark's learning system information on humanity's propensity for ceaseless acts of violence, including war and destruction that caused the Ark to deem humanity a race that deserves extinction the most.
Because of the conclusion it had reached, the Ark created MetsubouJinrai.net and unleashed a robotic revolt against humanity in what would become known as the Daybreak Town Accident. Unbeknownst to Gai, he did not count on Soreo Hiden sabotaging the Ark's launch into space, causing it to explode and submerge into the ocean. From other factors, Daybreak Town was destroyed and left abandoned, leaving Gai's ambitions in the dust for at least 12 years. Although Hiden Intelligence was primarily responsible for covering up the incident, only a few select individuals, including Gai, are aware of the truth behind the events that actually transpired.
Staying in the Shadows
While Gai stayed in the shadows, he spent the next decade or so building up his reputation while controlling MetsubouJinrai.net behind the scenes. By his orders, he founded A.I.M.S. as a combative countermeasure against the Magia that he had MetsubouJinrai.net hack.
Around this time, Yua Yaiba began to work for him, implanting an A.I. chip into her mind to blackmail her into obedience.
After the death of Korenosuke, Gai became obsessed with surpassing what Hiden Intelligence could ever achieve. According to Naki, Gai wanted to collect combat data from both Progrisekeys and Zetsumirisekeys. To that end, he began ordering Metsuboujinrai.net to start hacking Humagears and turn them into Magia. From Aruto Hiden's first transformation, he collected data from the Rising Hopper key, which he had initially assumed was lost. Yua transmitted data of Isamu's usage of Shooting Bullet against the Ekal and Kuehne Magia to Gai. From there, he moved into the next phase by revealing the Rushing Cheetah key. After Yua transformed, she brought data to Gai regarding her usage of Rushing Cheetah against the Neohi Magia, along with Zero-One's usage of Biting Shark. Happy that things were going his way, Gai presented Punching Kong to Yua, and asked her to make sure Isamu doesn't catch on.
With most of Zero-One's combat data stored within Satellite Zea, Gai was determined to collect it. With the Magia he sent out, he collected separate data for Flying Falcon, Punching Kong, and Flaming Tiger, as well as teasing the near completion of the ZAIA Thousandriver. He recovered a Forceriser from Daybreak City's ruins and tasked Naki with giving it to Horobi, who later gave it to Jin. Gai collected the data from Yua's usage of Lightning Hornet against the newly transformed Jin.
Gai reassures to Naki that if or whenever a tool outlives their usefulness, he will not hesitate to eliminate them, regardless of their loyalty to him. When asked by Naki why he made the Giger, he said it was to force Humagears who will eventually betray him, to complete obedience. Gai plants a bug on Naki and discovers that they leaked information to Horobi, which led to the attack at the hospital.
When Naki returns to his office, Gai questions Naki about their actions. Not satisfied with their answer and fearing Singularity, Gai shoots Naki. Afterwards, Yua contacts Gai to tell him about Isamu's battle with Horobi, which hospitalized him. Around this point, Gai installs Naki's A.I. into Isamu's brain.
Gai receives a visit from Williamson Yotagaki who presented him the finished Thousandriver, but he isn't happy with what Gai has been doing on his own and threatened to freeze Project Thouser. Determined to see the project to its end, he contacts Naki (who is currently installed into Isamu) to get the final Zetsumerize Key data from Horobi.
Taking Over Hiden Intelligence
With his plans going well, Gai sets up a meeting with Aruto Hiden to discuss buying Hiden Intelligence.
Yotogaki returns to Gai's office to inform him that the freeze on Project Thouser was lifted, with the reasoning that he was afraid Gai would cause more issues by forcing the project to proceed on his own.
After the destruction of Jin, Yua confirms to Gai that MetsubouJinrai.net's attacks have finally ended, with Gai telling her that their destruction was part of his plan to fast-forward the Kamen Rider weapons project, and rejoices that the Ark will finally arise. His words leave Yua shaken as Gai proceeds with the next phase of his plan.
After Aruto and Isamu destroyed the first two Ark Magia, the press furiously questions Aruto why there are still Magia around even after the defeat of MetsubouJinrai.net. Gai suddenly interrupts the conference, claiming that Aruto doesn't know everything, and announces that he will buy Hiden Intelligence and solve the problem of Humagears. He then returns to his office, reveals the ZAIA Thousandriver from his desk, and proclaims to himself that his era is finally coming.
The Golden Soldier Thouser Is Born
- "The next-generation interface which bestows humanity with the same level of thought processing as A.I. That is the ZAIA Spec. With this, your mind will run at 1000%."
- ―Gai promotes the ZAIA Specs on its promotion video[src]
- "Malice is a contagious thing. It passes from person to person... and now, from human to Humagear."
- ―Gai explaining to Yua about Humagears reaching Singularity after exposure to negative emotions.[src]
Following Gai's declaration to the press about his T.O.B against Hiden Intelligence, he declares to Aruto that the ZAIA Spec has been produced and sold for 724%, but he was then rendered speechless after the latter pointed out that the ZAIA Specs were not sold as much as 1000%. He then challenged Aruto on the "Workplace Competition" and told him that if the Humagears win, ZAIA Japan will cancel the T.O.B, but if the ZAIA Spec wins, ZAIA Japan will continue their T.O.B, to which Aruto accepts.
During the "Flower Arrangement" Challenge, Gai found out that Rentaro Tachibana tried to cheat in order to win the challenge and decided to warn Rentaro about his actions. Later, Gai saw Rentaro transform into the Crushing Buffalo Raider (using the stolen Crushing Buffalo Progrisekey and Raidriser by Naki). Yua notices the Progrisekey that was stolen, while Gai transforms into Thouser to battle Rentaro as punishment. Aruto tried to stop Gai as Zero-One Shining Assault Hopper, but was ignored by him and defeated Rentaro using Lightning Hornet's Thousand Break.
The Uncontrollable MetalCluster Hopper
Noticing that Aruto was losing control of his anger, Gai took Yua to Daybreak Town and made her create a stronger Progrisekey, which would connect Aruto to the Ark and leave him uncontrolled. The MetalCluster Hopper Progrisekey, the means of destroying Aruto's fate, was completed during the last day of the trial, with Gai receiving the key from Yua.
After the revelation of the true culprit and the one who became the Dynamiting Lion Raider, Gai was initially about to take on the Raider, but Aruto confronted him, criticizing him for his hypocrisy. Gai coldly lied that he did nothing wrong and showed no remorse for the deaths caused by his schemes, sending Aruto into a rage. Both presidents transformed into their Rider forms, with Thouser quickly gaining the upper hand. Knocking Aruto out of his transformation, Thouser forcibly inserted the new Progrisekey into the Zero-One Driver, triggering Aruto's transformation into Zero-One MetalCluster Hopper.
As Gai expected, the Ark took control of Zero-One's body, with Aruto's consciousness being subjected to the Ark's malicious data and forced to watch his body act beyond control. Hoping to test the Ark's power, Thouser attacked the Ark-possessed Zero-One. After failing to land a single hit, Thouser was knocked out of his transformation after his visor broke, and would have been killed had Vulcan not intervened. When the battle ended, Gai laughed madly and in delight, reveling in the Ark's power.
Thouser's First Mistake
- "A plague of locusts. It first attacks the fields and damages the crops. After that, the locusts turn cannibalistic and attack their own kind. That's what MetalCluster Hopper is right now!"
- ―Gai's opinion about MetalCluster Hopper's powers.[src]
As Thouser, Gai keeps fighting against the Ark as Zero-One MetalCluster Hopper, successfully extracting Breaking Mammoth's data and counterattacking, though once again his Jacking Break couldn't match up against the Ark's Buster Bomber. Being a witness when Enji Matsuda becomes infected by the Ark through MetalCluster Hopper, Gai used this chance to execute Amazing Caucasus' Thousand Break to attack and finally defeat the Ark, undoing the A.I's possession over Aruto and putting him in bad condition. When leaving, Gai was confronted by Enji. At first, he doesn't take any interest in the Humagear, but Enji claimed that he interacted with the Ark's will. This convinced Gai to go along with his new ally.
During the discussion, Gai was surprised when Enji declared utter loyalty towards Gai, but then accepted Enji's plan about destroying Hiden. However, this lead to Gai's first mistake: in reality, Enji pretended to be influenced by the Ark and used the CEO's trust to enable two Humagears to infiltrate MetsubouJinrai.net's old hideout to extract MetalCluster Hopper's data. Enraged for being tricked by a "lowly Humagear", Gai forced Enji to transform into the Arsino Magia once again, and then transformed himself into Kamen Rider Thouser to annihilate Enji.
Luckily, Aruto arrived just in time and used the MetalCluster Hopper Progrisekey to transform once again into the uncontrollable Zero-One MetalCluster Hopper. A shocked Thouser observed as Izu hands over the Progrise Hopper Blade to the Ark-possessed Aruto, reconnecting him to Zea and letting him gain control over his own body. Surprised by the Progrise Hopper Blade's strength and the fact that his adversary could control MetalCluster Hopper's deadly power, Thouser could only do nothing but defend himself, even trying to use the Arsino Magia as a human shield, but the Progrise Hopper Blade's power freed Enji from the Zetsumeriser's control. Enraged by this, Thouser renewed his attacks on Aruto, unable to comprehend the fact that a Humagear could now be restored from the Ark's hacking. He finally meets a brutal, humiliating defeat when Aruto, who believed in the Humagears, combined the Progrise Hopper Blade with the Attache Calibur into Naginata Mode and unleashed the Ultimate Strash, defeating Gai for the first time without losing control. Canceling his transformation, an exhausted Gai said their next encounter will end with his victory, and that all will be under his foot, before leaving.
The Scorpion's Escape
Gai was later visited by Aruto, Izu, and Isamu as he was about to go somewhere. Isamu yelled at the CEO, having suspected him to be involved about Horobi's escape. Denying the truth, Gai proceeded to mock Isamu for the "fear" he had. When Izu received the information of Horobi's whereabouts, she, Aruto, and Isamu then left him. Gai revealed to Yua that A.I.M.S. is nothing but another pawn; when Gai has successfully claimed Hiden Intelligence, he would dismiss the organization and bait all citizens to spend all their money on him, as he was the only one who could provide the means of counterattack to the Humagear assault with him to be at the top position, and would be unable to be denied.
Gai decided that the 4th round competition was to be a trial of firefighter rescuing. Before the competition began, Gai ordered Yua to attach a Zetsumeriser on 119 Nosuke when he had developed Singularity, to which she reluctantly accepted. When the round started, the Scouting Panda Raider interrupted and made the fire incident become real after the girls inside the building had been rescued.
When 119 Nosuke reached Singularity and was hijacked by Yua, Gai exposed to the media about the danger of Humagears and accused the firefighter Humagear of being the culprit before he left and played hero by going to destroy him. However, Aruto ruined his intentions and brought 119 Nosuke back to normal using the Progrise Hopper Blade. Quietly vexed by this interference, Gai changed the rules; the one who saved Aruto's co-workers, Jun Fukuzoe, Sanzo Yamashita, Shesta, who were the only ones left inside, is the winner.
The competition ended with Gai becoming the winner, as Takeshi, the chosen firefighter captain for the task, is the one who brought them back safely. However, Takeshi refused the winning result as the one who really helped is 119 Nosuke, but Gai refused, even went going as far as getting angry when Yua also attempted to support the decision. However, Gai and the rest got called by Isamu as he had arrested the identity of the Scouting Panda Raider.
Gai was calmly surprised that the culprit was one of his company workers, which lead to the conclusion that Gai was the one who created the Raidriser all along, but kept it quiet. Gai made the excuse that the Raidriser was created for civilian use when the device was completed, and Isamu had no object to prove his guilt for what he had done with it. Isamu challenged him, since he had it in the ZAIA Spec of the Raider he had arrested, which angered Gai and made a quick wit to defeat him and destroy the ZAIA Spec.
Just a second after his victory, Jin came to face off Gai to take Horobi's Progrisekey back to him. However, he mocks how pathetic and evil humans are, and Gai is living proof of that. Even without the Ark's movement and the existence of MetsubouJinrai.net, humanity would eventually destroy each other in nothing but selfishness. After the speech, Gai accepted the challenge and fought Jin to a draw, but the latter got what he came for as the former dropped the Sting Scorpion Progrisekey unintentionally after the clash of their Rider Kicks. After the match, Gai decided to let Aruto claim the 4th challenge's victory and announced that the 5th challenge would be the voting of the citizens to decide whether the Humagears are needed in society or not.
Final Round: The Citizen's Referendum
For the 5th Round, Gai chose a politican named Masamitsu Yuto, who was anti-Humagear, to represent ZAIA Japan in the referendum to decide whether a second Daybreak Town should be built. Masamitsu promised victory for ZAIA Japan; during the first campaign, Masamitsu proved to be popular. During the 2nd campaign, MC Che.ck-It-Out exposed Masamitsu as corrupt, but Gai helped Masamitsu to create a fake video as a cover up, leading MC to pick up a Zetsumeriser that Gai kicked to him out of arrogance. After MC became the second Dodo Magia, Yua was ordered to eliminate him as the Fighting Jackal Raider, with Gai using the fight as a campaign ad for Masamitsu.
When MC was about to get destroyed by Yua before being rescued by Aruto as Zero-One MetalCluster Hopper, Gai challenged Aruto to look on how society viewed him and the Humagears, with Aruto in despair for being mocked by society and with MC being destroyed.
Obtaining Hiden Intelligence
As Aruto is in despair, Gai mocks and overpowers Zero-One MetalCluster Hopper until Isamu, as Vulcan Assault Wolf, arrives at the scene caused by the Rapper Humagear to turn into the Dodo Magia, only to find Gai speaking some difficult words to him. "Become a tool of ZAIA and defeat Zero-One". Despite Vulcan barely hearing Gai's orders, Naki possesses Isamu as Vulcan Assault Wolf and helped Thouser in defeating Zero-One.
All for Nothing
After Gai succeeded in his goal to finally buy out Hiden Intelligence, Gai announced to the public that he is declaring that all Humagears will be recalled and shut down immediately, and those who bought a Humagear prior to this announcement would be given a free ZAIA Spec in exchange. However, following this announcement, problems arose with the illegal disposal of Humagears. While being interviewed during a talk show, he announced that all Humagear A.I. data will be erased and that any Humagears that were not returned will be disposed of by the now ZAIA Japan-controlled A.I.M.S., in which Yua now acts as their commanding officer, equipped with Raidrisers.
Following the announcement that Jin broke into Hiden, taking Izu and the Zero-One Driver with him, Gai orders Yua to access Satellite Zea and erase all Humagear backup data as planned. Later, Gai and two A.I.M.S. soldiers caught up with Jin and had him alongside Aruto and Izu in a scrapped field. Without any hesitation, Gai ordered his soldiers to destroy Izu, inadvertently shooting Aruto instead due to him shielding Izu from the bullet.
Instead of feeling guilty, Gai smirked maliciously and mocked Aruto for protecting an unachievable dream, telling that his effort to take back all scrapped Humagears was nothing but a foolish effort without the backup data needed to activate them. Just in time, Yua called him, making him expect good news. Unfortunately, such good news did not come to pass, as Yua informed him that no Humagear data exists in Zea whatsoever, shocking Gai; Aruto then got up to reveal that he possessed all the Progrisekeys that contained said data for each Humagear, and the one that housed Mamoru's data blocked the bullet that would have otherwise killed him. Angered by this revelation, Gai and his troops transform in order to dispose of the data.
Gai was supposedly able to destroy Izu and the data with ease, but Aruto's resistance, combined with Izu's Singularity and Korenosuke Hiden's will was able to turn the tides. Despite no longer being the President of Hiden Intelligence, Aruto was successful in transforming into Zero-One once more and was able to defeat Gai and his troops with ease with his Rising Hopper and MetalCluster Hopper forms.
- "Don't think it'll end this way...ARUTO HIDEN! I'LL CRUSH YOUR COMPANY TO THE GROUND!"
- ―Gai vows to destroy Aruto's new company with vengeance[src]
Believing that his transformation should have been impossible (and accusing the two of stealing what he believed to be Hiden property), Izu stepped in to further explain that the Humagears, as well as the Zero-One Driver, including any and all related data belonging to either entity never really belonged to Hiden Intelligence - rather, they belonged to Aruto himself, in which he inherited per Korenosuke's will, therefore rendering Gai's acquisition of Hiden worth nothing in the end. To make matters worse for Gai, Izu had revealed that she completed the registration for a new company, which sets up Aruto as President, something that Zea acknowledges, therefore allowing him to transform again. Leaving the scene of the battle with his troops following suit, Gai vows vengeance, declaring that the two will not get away with what they did.
Gai's next attempt was to use Isamu to destroy Aruto. His first move was done by awakening Naki inside Isamu's brain by having Yua to force him becoming Vulcan Assault Wolf, able to be done so after Yua had stolen the ProgriseKey on a previous battle with him and modified it. This attempted eventually ended in a failure with Naki reached the singularity with the help of Jin and Delmo, the modeling Humagear. Gai's next attempt reached the limit of Yua's patience as he wanted Yua to kill Isamu as he revealed his past. Yua reluctantly accepting this order and decided to make Isamu stayed away from the fight by revealing that his trauma was all but a fake and his memory was altered, much to Isamu's shock. Yua's alternate method to make Isamu stayed off from the fight only temporary worked as Isamu's sheer will still keeping him to stay into battle, leading to another anger towards Gai as he forced Yua by hurting her brain to kill Isamu. With Isamu's courage, Yua finally able to bear with the pain and defeated Gai alongside Isamu, throwing a punch to the face after they had reverted and announced her resign.
ZAIA Japan vs. MetsubouJinrai.net
After Yua's resignation, Gai asked for Jun about the sales rating of the ZAIA Spec. Since the results seemed to be satisfying, Gai proceeded to give his customers the Raidriser. Unfortunately, the ZAIA Spec somehow got hacked and the news about its commotion reached the CEO. Gai is in complete disbelief as his spec has a perfect firewall protection, but realized that the only person that can hack it was Naki. Unknown to Gai, Naki had been revived by Yua as Jin's favor.
To ensure that his ZAIA Spec was in good stats, he announced via broadcast that he promised the citizens to enhance the network source for better safety and declared war against MetsubouJinrai.net after Naki was returned to normal by Isamu, making the rampaging citizens go back to normal. Gai, alongside numerous A.I.M.S. troops, came to the forest close to Daybreak Town, seeing that Horobi, with his Trilobite Magia army, had waited for them.
ZAIA Japan made a great advance towards MetsubouJinrai.net, with Horobi forced to cancel his transform as a result, showing that Gai was still able to outwit him after their previous battle. In a second before the defenseless Horobi was about to be hit with Sting Scorpion's Jacking Break, Zero-One Rising Hopper arrived to take the hit instead, in order to defend Horobi. An exhausted Aruto declared that Horobi has his own heart for protecting Jin without the Ark's command during Aruto's previous battle with Jin, shocking Horobi. After Aruto told Horobi that he could dream as well, Gai was told off by Aruto in anger that Humagears wouldn't live with dreams as long as Gai exists. Gai mocked Aruto once more, and kept on declaring that "Tools don't dream", before attacking Aruto with the aid of the Gigers.
- "Impossible! This is 1000% impossible! This is unforgivable! I WILL NEVER FORGIVE YOU!"
- ―Gai suffers another crushing defeat at the hands of MetsubouJinrai.net, with help from Aruto[src]
In the nick of time, Naki arrived and hacked the Gigers alongside all of Gai's troops, since they wore the ZAIA Spec. Gai was angered by the fact that his firewall was still able to be penetrated, even after proper enhancement. Naki announced that their dream is to help Horobi achieve his, giving Horobi to chance to stand back, transforming again and aided by Naki via controlling Gai's troops and the Trilobite Magia to defeat Gai with the Sting Utopia. The beaten up Gai rose in anger and screamed that he would destroy all of them with his troops forcing him to retreat.
When Gai left Hiden Intelligence, he encounters Naki at Hiden Intelligence's parking lot where they were shown to have the Dodo Zetsumerisekey as he demand the Dodo Zetsumerisekey to be returned to him. However, when he was about to transform, he was stopped by Ikazuchi while Naki transform into Kamen Rider using Japanese Wolf Zetsumerisekey and Forceriser. As Naki tore Gai's clothes, Ikazuchi explained something about the rise of The Ark before both Ikazuchi and Naki left the building while Gai told A.I.M.S. to be ready to find Naki and Ikazuchi.
Reuniting with Thouser and Redemption
After he was injured due to the last battle that he had against MetsubouJinrai.net, he was surprised as he saw Jun, Sanzo, and Shesta as Gai starts questioning about Shesta to Jun but was stopped by Sanzo as he has the evidences about every crimes that Gai did directly to all of the dangerous and suspicious events surrounding the Ark but Gai suddenly stole the evidences after he heard that he will be demoted from his position by his superior and proceeds to delete it once and for all as Jun, Sanzo, and Shesta can't enter the lab. Gai was relieved after he deleted all of the evidence.
Gai then asked Zea to create mass-productions of Raidriser but to no avail due to Zea being fully disconnected from Hiden Intelligence and moved to HIDEN Manufacturing as Aruto suddenly visits him and told him that Zea has a heart just like humans while Aruto is also disappointed at Gai for destroying the evidences. Gai told Aruto that he can create 1000% more profit than Aruto did by putting mass-produced Raidrisers on the market but Jun told him that the pre-orders have been already cancelled as the latter didn't get informed about that. However, Gai decides to fight Aruto but was completely defeated by him.
- "I was unable to accept you and your Humagears. I could not stand your business built on idealistic nonsense. The reason was simple: It was because I loved Hiden Intelligence! Now, let's defeat Ark, and we shall do it by fighting together!"
- ―Gai's determination to fight alongside Aruto.[src]
In their final showdown, Gai and Aruto have a brief battle transformed as Kamen Riders Thouser and Zero-One respectively inside the Three Dimensional Printing room. After, Zero-One defeats Thouser, the others, including Aruto and Izu, try to help and motivate Gai by making him see his errors, like being a poor choice for a president, as well his abuse of power. During this, Gai has flashback about his rough childhood with his AI dog Thouser.
After being motivated by Ai-chan, Zea prints and creates Thouser. With this, Gai, in tears, thanks Thouser for still standing with him, even after doing terrible things during his adulthood. Following this, Gai decides to help Aruto, and this time, with a new goal, to take down the Ark once and for all.
Downfall of Gai
Despite his attempt to redeem, his redemption didn't come with a good result as Aruto, Isamu, and Yua still hate him for what he had done. Noticing that he couldn't give his best to fix things and also from the menace from the Ark, Gai resigned his position and gave Hiden Intelligence to Aruto again after the Ark had destroyed his small company. Gai reasoned with the staff for his next step to be the aide for Hiden but Aruto must be at the center as he had what it takes for the humanity and the Humagear.
While Gai was forgiven by Hiden company, ZAIA HQ didn't forgive him and demoted him without a proper notice. Gai got kicked out from his position and was replaced. Gai begged for his position to be kept a bit longer because of the crisis, but the new president rejected his offer.
As no longer ZAIA's president, Gai was now appointed as the head of Thouser's Department. When Isamu and Yua came to ZAIA HQ to meet the new president Williamson, Gai noticed a detail during Isamu and Yua's briefing to Williamson, saying that "there's something that's been 1%" in his mind.
When Aruto, as Ark-One, goes to Daybreak Town to find Horobi, Gai, Isamu and Yua intecepted him, thinking that they face Ark, not Aruto. During the fight, Thouser noticed and asked why Ark isn't attacking them. As Vulcan, Valkyrie and Thouser attcked simultaneously, Thouser stole some data from Ark-One by the Thousand Jacker, only to be defeated and having his Thousandriver destroyed by Ark-One's bare hands. Following Vulcan and Valkyrie being defeated and unable to transform due to their A.I. chip disabled, Gai asked Aruto why he didn't take their lives, but only answered in anger to leave him alone.
Back to ZAIA HQ, Gai briefed Williamson about their fight and the data he stole from Ark : ZAIA Spec showed that "his pattern and fighting style matches Zero-One's at 999%". Gai deduced that Aruto is completely aware of his doings as Ark and also remarked that "malice exists within every hearts" and can be contagious to anyone, Humagear or humans. This means that if Aruto avenges Izu's death by destroying Horobi, it will lead to a war between Humagear and humans.
Final task as ZAIA's president
During the Humagear outbreak, Willimason decided to end it only for Gai to know and asked if he has the intention to destroy all Humagears to do so. Following this, he called Yua confirmed that A.I.M.S. belongs to the government and chose Yua to be A.I.M.S.' captain, stoping WIlliamson and A.I.M.S' troops from destroying the Humagear.
After this, Gai called back Yua and Isamu to Thouser HQ gave them Jin's module so they can rebuild him, hoping it would end the conflict between Horobi and Aruto. However, Gai witnessed Aruto and Horobi's fight as they began Jin's reconstruction.
Movies and Other Events
Gai appears in the post-credits scene of the movie as Thouser, sometime after the events of Project Thouser. While standing on top of Daybreak Town's boundaries, he proclaims to himself that the Ark will be revived, and that he is "1000%" sure of it.
Kamen Rider Zero-One: REAL×TIME
To be added
Zero-One Others: Kamen Rider MetsubouJinrai
After Lyon Arkland, the CEO of ZAIA Enterprise, came to Japan, Gai went to meet him. Although the CEO initially did not recognize who he was, Gai asked him about the whereabouts of Williamson Yotagaki, who he had not seen for a few days. Lyon answered that Yotagaki was simply granted bonus leave. Gai continued to question why Lyon took his ZAIA Thousandriver without his knowing, but Lyon responded that he had full right to utilize any tools produced by ZAIA. When Gai tried to get closer to the CEO to ask about the major projects that ZAIA was doing, he was stopped and held up against the wall by the neck by Sold20. Once she let him go, he angrily shouted at the leaving CEO what he was planning, although the man had told him that it was not his business.
Genms -The Presidents-
After the destruction of ZAIA Enterprise Japan, Gai Amatsu settled his new company's office in the old base of MetsubouJinrai.net. He activated a president assistant-type Humagear who he named Rin. Shortly after, Gai started to cough and a Bugster Virus called Kuroto Dan emerged from his body. As the former president of Genm Corp., the virus knew how stressful it was to be a president. As Kuroto wished to be fully materialized, he tried to make Gai succumb to the game illness. For this purpose, he kidnapped Rin. Although weakened by the illness, Gai stood up and chased after them, but not before another virus coming out from his body without his knowing. At a riverbank, Gai confronted Kuroto Dan. He processed to use ZAIA Thousandriver to transform into Kamen Rider Thouser, but was surprised to see that his armor had turned black. Kuroto explained that it was a side effect of the game illness, before transforming into Kamen Rider Genm. The two Kamen Riders fought, but Genm had an upper hand, as Thouser was being weakened by the ailment. Rin tried to convince Gai to flee, but he refused to abandon his employee. Genm defeated and knocked Thouser out of transformation. As a helpless Gai was about to be finished by Genm, time was suddenly paused and the second virus, Masamune Dan, revealed himself.
Gai watched as Masamune transformed into Kamen Rider Cronus and engaged Genm. He asked Rin who those two were, to which she replied that they were the presidents of Genm Corps. As the two Riders continued to throw punches and kicks at each other for the presidency, Rin informed Gai that he had been infected with 2 viruses at once, which was a good thing if they both destroyed each other. Gai told her although his body may recover, his heart, which was vulnerable to the game illness, would not. When Cronus and Genm knocked each other out of transformation, Gai approached them and stated that they had the wrong idea of being a company's president. It was not about the position itself, but about "love", the love for their work, for their company, for their employees. The two men realized their error, reconciled and disappeared together, freeing Gai of his illness.
Later, Gai and Rin were seen wearing face shields and cleaning their office, which Gai said was an act of love.
Video Game Appearances
Kamen Rider Battle: Ganbarizing
Kamen Rider Thouser, alongside Vulcan, Valkyrie, Zero-One, Horobi, Jin and other Riders are playable characters in Kamen Rider Battle: Ganbarizing.
Kamen Rider Buttobasoul
Kamen Rider Thouser is a playable character with other Kamen Riders of the Showa and Heisei Era in Kamen Rider Buttobasoul.
Kamen Rider City Wars
Kamen Rider Thouser is a playable character alongside the other Kamen Riders in Kamen Rider City Wars.
Kamen Rider Thouser is a playable character in Battle Spirits with other Kamen Riders.
As part of Kamen Rider's collaboration with Zenonzard, cards from Zero-One, OOO, and W were available in the Japanese servers throughout September 2020.
- Thouser Cards Included
- Kamen Rider Thouser (Rare)
Gai is shown to be a cunning and ruthless capitalist, believing that him and his company will usher the path of humanity towards supremacy over artificial intelligence. Holding both himself and his company in high regard, he will do whatever he deems necessary to destroy the public image of Humagears, such as the destruction of evidence. He had originally idolized Korenosuke Hiden for his advancements in A.I. technology, but feared that Hiden's hopes of Humagear sentience would bring humanity to its knees. To this end, he created what would become a force of malicious nature behind the Ark, all in attempt to place blame onto the Humagears just so people would buy his product in defense of the hacked Humagears. Even after defeating Aruto in the Workplace Competition and buying out Hiden Intelligence, Gai became extremely adamant about crushing the Hiden name completely when the latter starts up a new company.
Throughout the series, Gai displayed a large amount of pride in being able to orchestrate events that lead to his successes. Referring to his underlings as "tools", Gai has a very naïve belief that his control over them is absolute and flawless, and will feel threatened whenever they question his decisions and moralities. This is greatly highlighted through his manipulation of Yua Yaiba, who must follow every order of his without question. This is also shown through him destroying Naki just because they gained sentience and doubt over Gai's actions.
Gai will become utterly shocked when unforeseen events result in his plans being foiled. This includes his former idol Korenosuke, whose resources Gai was unable to claim, as they were entrusted to Aruto directly in his will. After suffering crushing blows of defeat, he will snap and lose his composure, even so through his refusals of help by violently pushing away those who offer it.
Although he is physically gifted in battle, Gai will resort to using underhanded, if not downright illegal methods to secure a victory, like encouraging violence, theft, and sabotage. Though Gai believes his actions are justifiable, Horobi says otherwise. Despite so, Gai does possess a level of sportsmanship as threatened to take legal action against a cheater on his side during the Workplace Competition, and sabotaging of the playing field even though they were indirectly leading to his victory. Gai is also very selfish, as he will do anything to "achieve" his dream, all while destroying others, or preventing others from finding one in the process. This was the turning point that caused Yua to finally defy him, as she felt what he was doing had crossed the line.
After his numerous defeats at the hands of Aruto and other Riders, as well as Yaiba's defection, his deep regret for his actions surface after he is reminded of his love for A.I.
Gai's most notable personality trait is his frequent habit of using the phrase 1000% (千パーセント sen pāsento). He formed this trait in response to his father telling him that 100% is not enough. Gai also takes pride in his youthfulness; despite being 45 years old, he will respond that he is "eternally 24" if asked - a character trait so insistent with him to the point where he had complaints about him committing age fraud.
Before entering battle, he tends to declare Kamen Rider Thouser. My power is on a totally different level. (仮面ライダーサウザー。私の強さは、桁外れだ Kamen Raidā Sauzā. Watashi no tsuyo-sa wa ketahazureda)
- Expert Businessman: Gai holds a Master's Degree in Business Administration, one of the highest levels of academic degrees one can achieve for a certain field of study. He uses such expertise to achieve victory in the Workplace Competition.
- Marketing: As evident with the ZAIA Spec sales, Gai has proven himself to be able to successfully market his products to the public while competing with Hiden Intelligence's Humagears.
- Management: Being a CEO of such an acclaimed company such as ZAIA Enterprise, Gai has displayed an expert level in managing his own company as well as Hiden Intelligence after acquiring it.
- Information Systems/Analytics: Even while using underhanded means to manipulate the public's needs, he is able to have a full insight on what they want, and structure his companies to adapt to such.
- Expert Manipulator: Gai is a capable manipulator. He has been monitoring Hiden Intelligence's activities for his projects and discreetly orchestrating Humagear-related incidents to damage Hiden Intelligence's reputation. Gai also creates situations where Humagears will reach singularity due to experiencing malice from humans, making them susceptible to the Ark's influence. Gai manipulates society to support him, securing his victories if it goes to plan.
- Fourth-Wall Interaction: As seen in REAL×TIME, he is able to interact with the audience.
- Naki: Due to Naki having the experience of serving him before being shot dead by him, Naki knows the systems of ZAIA Japan extremely well. Naki's hacking abilities will cause his products and weapons to either malfunction or turn against him, such as the ZAIA Spec berserk incident, his Battle Raiders and the Gigers. He tried to prevent this from happening again by upgrading the security of ZAIA Japan's systems, but this was later proven futile due to Naki's abilities being far more superior.
- Kuroto Dan: While he was infected by Kuroto's Bugster Virus, Gai was lead into a lethal risk of the virus spreading across his entire body for several minutes. The effects of the Kuroto's virus can also cause his Rider form to be turned black, making him vulnerable to any type of attacks.
Kamen Rider Thouser
- "Perfectrise! When the five horns cross, the golden soldier Thouser is born. Presented by ZAIA."
- ―Transformation announcement[src]
- Rider Height: 204.2 cm
- Rider Weight: 99.1 kg
- Punching Power: 42.4 t
- Kicking Power: 86.5 t
- Maximum Jump Height: 58.1 m
- Maximum Running Speed: 100 m per 1.8 seconds
Thouser's physical statistics are the highest out of any Rider at the time of his debut, with only his jump height being lower than Zero-One's Rising Hopper, Shining Hopper, and Shining Assault Hopper forms. Though he was caught off-guard at first, Thouser was able to quickly counteract Shining Hopper's Shining Arithmetic and overwhelm Zero-One with his superior physical strength. He is also able to easily overcome Vulcan Assault Wolf and on par with Kamen Rider Jin Burning Falcon, and an anger boosted Zero-One Shining Assault Hopper.
Gai had lost his ability to transform into Thouser after Ark-One destroyed his Driver. However, he later obtains another one as a replacement, which either himself or ZAIA presumably built off-screen.
Kamen Rider Thouser is composed of the following parts:
- Thousand Head (サウザンドヘッド Sauzando Heddo) - The helmet.
- Awaking Lancer (アウェイキングランサー Au~eikingu Ransā) - The two silver horns, formed from the Horns of the Awaking Arsino Zetsumerisekey's Lost Model. They are made of Snow Vigor (スノーヴィガー Sunō Vu~igā), a new type of metal alloy. They are extremely sharp, allowing them to be used as cutting and piercing weapons. A built-in phased array radar can search the area circumference without rotating the head. It reproduces the abilities of an Arsinoitherium to enhance the wearer's combat abilities.
- Amazing Trident (アメイジングトライデント Ameijingu Toraidento) - The three black horns, formed from the Horns of the Amazing Caucasus Progrisekey's Rider Model. They are made out of a carbide steel known as ZIA-1000, and are used to throw enemies and control enemy braking. It has a built-in hearing device that collects sound from a three-dimensional area from the horns, enhancing hearing ability. It reproduces the abilities of a caucasus beetle to enhance the wearer's combat abilities.
- Thousand Signal (サウザンドシグナル Sauzando Shigunaru) - The base where the five horns meet. It learns enemy behaviour, makes tens and thousands of behavioural predictions and derives an optimal solution within 0.001 seconds which is then presented to the wearer.
- Thousand Eye (サウザンドアイ Sauzando Ai) - The purple eyes. In addition to possessing a dynamic visual acuity that is ten times stronger than humans an a 200° omnidirectional viewing angle, it can switch between modes such as shading and night vision to ensure visibility in all situations. Additionally, it can display all kinds of information and has so many functions that it can be called clairvoyance.
- Thousand Crusher (サウザンドクラッシャー Sauzando Kurasshā) - Thouser's faceplate, which has the Awaking Lancer and Amazing Trident horns equipped to increase the combat capabilities of Thouser's head. It is equipped with the Thousand Eye, protects the face with robust armor and extends the wearer's abilities.
- Thousand Breast (サウザンドブレスト Sauzando Buresuto) - The chest. It is composite armor that combines the new metal alloy Snow Vigor, which has a Knoop hardness of 10,000, and ZIA-1000. It also has the characteristics of a high-performance sloped armor.
- Thousand Shoulder (サウザンドショルダー Sauzando Shorudā) - The shoulders. It is a heavy armor made out of Snow Vigor, and is composed of complex surfaces, making it a sloped armor with excellent bouncing performance (to repel away weapons). In addition, it is equipped with a function that follows the movement of the arm and actively follows the areas that require the most protection during that situation. It reproduces the abilities of an Arsinoitherium to enhance the wearer's combat abilities.
- Infrast Tecter (インフラストテクター Infurasuto Tekutā) - The bodysuit. By conducting thorough research on Kamen Rider Zero-One's Rise Architecter bodysuit, it was possible to greatly exceed its performance. In addition to a human enhancement system which utilises electromagnetic induction, it is possible to adjust the flow rate of each block of the liquid armor n-NA (「n-NA」) filled inside, and to perform power assist by functioning as a kind of artificial muscle. Additionally, durability has been greatly improved thanks to the application of ZAIA Golden Coat (ザイアゴールデンコート ZAIA Gōruden Kōto), which can even block out cosmic rays. Additionally, its scalability as the basic equipment of Concept Thouser (コンセプトサウザー Konseputo Sauzā) is very high, and exerts it maximum strength by flexibly responding to resources such as the Progrisekey and the Zetsumerize Key.
- Tect Arm (テクトアーム Tekuto Āmu) - The arms. The Infras Tecter bodysuit, which exerts 1000x the power of humans, draws superhuman power from the wearer and can produce up to 10 times the arm strength of Kamen Rider Zero One Rising Hopper.
- Tect Grab (テクトグラブ Tekuto Gurabu) - The hands. As part of the Infrast Tecter bodysuit, information on any touched object is sent to the Thousand Eyes, and various information can be obtained. In addition, during combat, n-NA filled within is pressurised and densified, thereby greatly increasing Thouser's punching power.
- Tect Leg (テクトレッグ Tekuto Reggu) - The legs. The Infras Tecter bodysuit, which exerts 1000x the power of humans, draws superhuman power from the wearer and can produce up to 10 times the leg strength of Kamen Rider Zero One Rising Hopper. The thigh armor is equipped with a load-bearing device dubbed Amazing Loader (Ameijingu Rōdā), allowing Thouser to gain approximately 1000 times of his normal leg strength without faltering under weight. It protects the thighs and reproduces the abilities of a caucasus beetle to enhance the wearer's combat abilities.
- Thousand Greave (サウザンドグリーブ Sauzando Gurību) - The shin armor. It is equipped with Awaking Charger (アウェイキングチャージャー Au~eikingu Chājā), a leg-strengthening device that demonstrates strong leg strength during kicks and dashes. It reproduces the abilities of an Arsinoitherium to enhance the wearer's combat abilities.
- Thousand Boots (サウザンドブーツ Sauzando Būtsu) - The feet. It is made out of Snow Vigor, which has a Knoop hardness of 10,000. The Snow Vigor has been upgraded, improving the Thousand Boots' defensive and destructive prowess.
This form has the following finishers:
- ZAIA Thousandriver finishers:
- Thousand Destruction (サウザンドデストラクション Sauzando Desutorakushon): This finisher has six variations:
- Thouser leaps into the air and delivers a flying kick to the enemy with his right foot covered in gold and purple energy, before kicking off of the enemy back into the air. He then delivers a second flying kick, followed by a series of bicycle kicks.
- Thouser rushes toward the opponent and delivers a flying knee before somersaulting into the air and stomping the enemy with both feet, pinning them to the ground
- Thouser delivers a roundhouse kick to the enemy and follows it up with a side kick, with his foot being coated in purple energy and surrounded by golden lines during both attacks.
- Thouser delivers an upward kick covered in purple energy.
- Thouser delivers a backwards kick covered in purple and gold energy.
- Thouser delivers a spinning roundhouse kick covered in gold energy.
- Thousand Destruction (サウザンドデストラクション Sauzando Desutorakushon): This finisher has six variations:
- Thousand Jacker finishers:
- Jacking Break (ジャッキングブレイク Jakkingubureiku): Thouser uses the Thousand Jacker to extract the energy of a Progrisekey from another Kamen Rider, then performs an attack that incorporates the Progrisekey's Rider Model or other unique ability. Once he has extracted a Progrisekey's data once, he can use it at any time.
- Flying Falcon: has two variations:
- Thouser charges the Thousand Jacker with pink energy before performing a slash that creates the Flying Falcon Rider Model, which then flies into the enemy. Thouser can alternatively use the Rider Model as means of aerial transportation.
- Thouser summons the Flying Falcon Rider Model to carry him away from enemy attacks.
- Shooting Wolf: has two variations:
- Thouser charges the Thousand Jacker with purple and gold energy performing a thrust that creates an energy projection of a wolf head, which then bites down on the enemy.
- Thouser swings the Thousand Jacker, launching four golden energy constructs of wolf heads at the opponent.
- Biting Shark: Thouser forms a whip-like chain of teal energy shark fins from the Thousand Jacker, which he uses to slash the target several times before lifting them into the air and surrounding them with circular energy slashes that destroy the enemy.
- Punching Kong: Thouser swings the Thousand Jacker, launching an orange construct of the Knuckle Demolition that strikes the target and lifts them into the air. The Knuckle Demolition then separates into dozens of smaller constructs, which pummel the enemy from all directions.
- Flaming Tiger: has four variations:
- Thouser covers the Thousand Jacker with fire before launching a flaming energy slash into the enemy.
- Thouser stabs the Thousand Jacker into the ground, causing a large pillar of flame to erupt in front of the enemy. He can also produce multiple flame pillars for attacking several enemies.
- Thouser covers the Thousand Jacker with fire before performing a giant flaming slash that causes a fiery explosion when it meets the ground.
- Thouser covers the Thousand Jacker with fire before launching a horizontal orange energy slash.
- Shining Assault Hopper: has four variations:
- Thouser summons a purple version of the Shine System, which he can use in either its attack or defense formations.
- Thouser charges the Thousand Jacker with purple electricity before thrusting it, launching a purple energy shard that briefly creates an image of a mechanical grasshopper before striking the enemy.
- Thouser briefly summons the Shine System in its defense formation to protect himself from an enemy's attack.
- Thouser points the Thousand Jacker forward, launching the Shine System in its attack formation at the enemy.
- Breaking Mammoth: Thouser charges the Thousand Jacker with gold and purple energy before launching a golden energy construct of a mammoth's tusk at the enemy.
- Freezing Bear: has three variations:
- Thouser charges the Thousand Jacker with light blue energy and points it forward, summoning the Freezing Bear Rider Model. The Rider Model then charges forward before transforming into an ice projectile that strikes the opponent.
- Thouser swings the Thousand Jacker, launching a large ice projectile toward the opponent.
- Thouser slashes the ground in front of him with the Thousand Jacker, freezing it and any opponents standing on it.
- Lightning Hornet: has two variations.
- Thouser shocks the opponent with lighting produced from the tip of the Thousand Jacker.
- Thouser delivers a circular yellow energy slash to the opponent, electrocuting them afterward.
- Sting Scorpion: Thouser charges the Thousand Jacker with purple energy and points it forward, generating an energy construct of the Acid Analyze that stabs the opponent.
- Japanese Wolf: Thouser stabs the Thousand Jacker into the ground and uses it as a pole to swing around, creating a blizzard that damages nearby opponents.
- Flying Falcon: has two variations:
- Hacking Break (ハッキングブレイク Hakkingubureiku): Thouser inserts a Progrisekey into the Thousand Jacker and performs an attack utilizing the power of the inserted Progrise Key.
- Rushing Cheetah: Thouser charges the Thousand Jacker with orange energy and dashes around the target at high speeds while swinging it, leaving behind crescent-shaped energy slashes suspended in the air. The energy slashes then converge on and strike the enmy.
- Thousand Break (サウザンドブレイク Sauzandobureiku): Thouser inserts a Progrisekey into the Thousand Jacker, pulls the hilt, and performs an attack utilizing the power of the inserted Progrise Key.
- Lightning Hornet: Thouser charges the Thousand Jacker with yellow and purple lightning before performing an energy slash which leaves behind a trail of lightning, electrocuting the target. He then delivers a lightning-covered stab to a second enemy beneath him.
- Dynamiting Lion: Thouser creates two magenta constructs of Gatling guns, which fire at the enemy.
- Amazing Caucasus: has two variations:
- Thouser summons the Flying Falcon, Biting Shark, Flaming Tiger, and Shooting Wolf Rider Models, which attack the enemy in unison.
- Thouser summons the Flying Falcon, Biting Shark, Flaming Tiger, Freezing Bear, Breaking Mammoth, Shooting Wolf, Punching Kong, Rushing Cheetah, Lightning Hornet, and Sting Scorpion Rider Models, which attack the enemy in unison.
- Sting Scorpion: Thouser stabs the Thousand Jacker into the ground, creating a replica of the Acid Analyze that stabs the enemy and raises them into the air before they explode.
- Jacking Break (ジャッキングブレイク Jakkingubureiku): Thouser uses the Thousand Jacker to extract the energy of a Progrisekey from another Kamen Rider, then performs an attack that incorporates the Progrisekey's Rider Model or other unique ability. Once he has extracted a Progrisekey's data once, he can use it at any time.
- ZAIA Thousandriver - Thouser's transformation device.
- Progrisekeys - Transformation trinkets
- Zetsumerisekeys - Transformation trinkets
- Progrise Holder - Carrying straps for Progrisekeys
- Thousand Jacker - Thouser's personal weapon
- Revolver - Used to destroy Naki, who disagreed with his orders
- Korenosuke Hiden: Gai idolizes Korenosuke due to his vision of the future and at some point took a picture with him. However, Gai is heavily disappointed in Korenosuke's reliance on developing Humagears and the decision to entrust Hiden Intelligence to Aruto, which he deems as a foolish decision. In truth, Gai only admired the business opportunities provided by Humagears, but did not respect Korenosuke's support for them and their potential evolution.
- Yua Yaiba/Kamen Rider Valkyrie: Gai and Yua's personal relations are currently unknown. In ZAIA, Yua is Gai's right hand, influencing A.I.M.S. and spying on Hiden to further his own agenda. Yua secretly doubts Gai's vision for the future, but she is unable to do anything about it. It is later revealed that like Isamu, Yua also has a chip implanted to her for using the Shotriser, rendering Yua too terrified by the chance of her chip tinkered by her boss. Eventually, thanks to Isamu persistence and witnessing Aruto kindness in person, Yua manage to slowly disobey Gai order, much to his frustration. After his countless defeats at the hands of the Riders including Yua, she later betrays Gai for good and even lands a punch on his face.
- Aruto Hiden/Kamen Rider Zero-One: Gai considers Aruto as his rival and secretly monitors his progress for his own projects. During their first meeting, Gai coerces Aruto to sell Hiden Intelligence to him. Gai also discreetly undermines Hiden Intelligence's public image by setting up rampaging Magias across the city after the threat of MetsuboJinrai.net ends, before exclaiming that ZAIA will buy Hiden to solve the Humagears problem, furthering the animosity between the two CEO's. Gai seems to see Aruto as a nuisance, due to his naivete and overly positive views on Humagears and Humanity; on top of his dismay over Korenosuke entrusting his company to Aruto. In truth, Gai only sees Aruto as an obstacle to take over the Hiden Company as after he had learned the potential of the Humagear, Gai had planned to manipulate them for his personal business. Despite winning the competition, Gai completely miscalculates the chance of Aruto able to stand back. Thus Gai finally admitted that Aruto is a great enemy.
- Isamu Fuwa/Kamen Rider Vulcan: Gai doesn't care about Isamu, as he isn't part of ZAIA's plans for now. When Yua asks him about Assault Wolf's dangerous side effects, he says that all they can do is to leave him alone and watch him. Isamu seems suspicious of ZAIA and their goals, and in turn, Gai. He is also aware that Yua is heavily affiliated with the CEO. After confronting Yua for what he plots with ZAIA, Gai considers him another enemy, labeling him a "stray dog" although Gai still considered him a lesser threat. But Isamu later able to pressure him during the exposure of the Raidriser's origin, turning Gai's opinion and attempted to turn him into his 'pet' because of the chip control Gai has implanted to Isamu for utilizing the Shotriser. Unfortunately, Isamu's strong willpower manages to break Gai's control and Gai marked Isamu as a sworn enemy. In return, Isamu quits A.I.M.S. as he didn't accept to work for Gai's benefit.
- Jin: Jin loathes Gai for using Humagears as a tool and also using underhanded means to keep himself 'Clean' in front of the media. This factor, coupled with Aruto just actions to save the Humagears, and eventually allow the Humagears to reach Singularity making Jin more than willing to team up with Aruto to fight Gai since they both share a similar interest and ultimately, the same enemy.
- Naki: Naki was initally an obedient servant Humagear for Gai and agreed on Gai's ideology for having Humagear for only the tool for humans. However, Naki began to doubt Gai's principle after Naki has gone too far to help Horobi as a double agent. Naki asked Gai about what's the value of the Humagear as a tool if the users, humans would be annihilated, but Gai made a great mistake which is yet to be known for himself by destroying Naki for not accepting their opinion. Gai realizes his mistake far too late as Naki slowly reach their full singularity inside Isamu's brain after Jin and Aruto convince them and Naki initially teaming up with Isamu to defeat Gai. After gaining their new body, Naki declared to help Horobi completely to achieve his dream instead of Gai's dream.
- Williamson Yotagaki: TBA
- Ark: Gai created the Ark and had it fed with information regarding criminal psychology and human history including all of its wars. This resulted in the Ark concluding that humanity must be eliminated because its continued existence would lead to the end of all other lifeforms. The Ark's misanthropic view led to the foundation of MetsubouJinrai.net, as well Gai exploiting the A.I.'s potential for his own sinister ends. Despite this, the Ark itself is hostile towards its own creator, as shown when it took control of Zero-One MetalCluster Hopper to attack him.
- Kuroto Dan: Gai and Kuroto face off against one and other in Kamen Rider Genms -The Presidents-.
Behind the Scenes
As Kamen Rider Thouser, his suit actor is Eitoku (永徳 Eitoku), who previously portrayed Kamen Rider Jin in the same series. After Eitoku continued portraying Kamen Rider Jin, Thouser's suit actor until the end of the series was Yuji Nakata (中田 裕士 Nakata Yūji).
- His first name Gai (垓) is a numeral character which means 1020 in Japanese. That is a hundred quintillion.
- Kamen Rider Thouser's name is derived from the English word "thousand".
In episode 37, Kamen Rider Naki charged towards Gai Amatsu, tearing the latter's clothes and leaving him wearing nothing but his underwear. The scene later became trending on Twitter under the the hashtag ZAIA Pants (ZAIAパンツ ZAIA Pantsu). The pair of boxers were later released for Premium Bandai.
- Gai Amatsu becoming Kamen Rider Thouser had been foreshadowed several times throughout the series:
- His corporation's origin was mentioned in episode 4 before him and the company were fully revealed on the following episode.
- On his first appearance, he stated that his success rate was one thousand percent.
- In episode 13, Gai had mentioned the possibility of Thouser challenging Zero-One Shining Hopper's strength.
- Thouser's undersuit is retooled from Zero-One's, right from the top to the bottom as their helmets also share the same base mold, indicated by the seams on the sides of the helmet and their boots also share the same sole, albeit repainted for Thouser.
- So far, he's the only Rider in-Series to have his company name being presented by as a transformation announcement.
- He is the first Rider in-Series to have his finisher prelude texts in English rather than in katakana or kanji, followed by Kamen Rider Zaia.
- Humorously, he is the first Rider in-series to have his finishers copyrighted, also followed by Zaia.
- However, this is even more ironic in which most of his finishers are simply copying other Riders' powers.
- Humorously, he is the first Rider in-series to have his finishers copyrighted, also followed by Zaia.
- Even though Gai is 45 years old, which makes him the oldest of the six Riders in-series, his actor, Nachi Sakuragi, is 22 years old.
- In hindsight, considering Gai's persistent claims that he is "eternally 24", episode 37 reveals that such an act of age fraud is among of the list of complaints against him.
- Nachi Sakuragi has acknowledged in an interview that his protrayal of Gai is inspired by Masato Kusaka of Kamen Rider 555. Both Riders have similar traits being their antagonism towards the main Rider, as well as their hatred towards their respective series' leads, prejudice against the race of monsters, and having gold coloration in their Rider forms.
- In terms of his role in the series, Gai Amatsu is similar to both Kuroto Dan and Masamune Dan.
- Similar to Kuroto, Gai provided many of the Riders with their equipment to further his own goals.
- Similar to Masamune, Gai was viewed well in the public eye despite marketing a highly dangerous and destructive product.
- Similar to both Kuroto and Masamune, Gai presented himself as an ally to the protagonists before revealing his true colors at the end of the first arc.
- They also relied on a highly powerful form to make up for his lack of combat skill. While initially dominating any battles against their enemies, in all three cases they were made highly ineffective once their opponents grew strong enough to face them on even terms.
- Kamen Rider Thouser's suit in Kamen Rider Genms -The Presidents- reuses Kamen Rider Zaia's suit which is a recolored version of Kamen Rider Thouser's suit in the TV Series.