Icon-zero-one.png This article is about a/an character in Kamen Rider Zero-One.

Williamson Yotagaki (与多垣ウィリアムソン Yotagaki Uiriamuson) is the chief of ZAIA Enterprise's Research and Development department before he was transferred to Japan Branch and took over as ZAIA Japan's 2nd CEO after Gai's dismissal. He is the secret benefactor behind Jin's revival.


Williamson was originally a member of the Ark development team alongside with his junior Gai Amatsu to develop the Ark for humanity's hope but he became disappointed to Gai after the latter decide to put malice on the Ark and use it for evil and for his own interests.

Later, Gai was appointed by ZAIA Enterprise as the president of Japan Branch, while Yotagaki was appointed as the chief of Research and Development department of ZAIA Enterprise.

Project Thouser

Yotagaki arrived at the Japanese office to meet Gai as he told the latter about the completed ZAIA Thousandriver as he also knew about Naki's AI Chip has been installed into Isamu Fuwa's head without his permission. Yotagaki then told Gai that he will send back the ZAIA Thousandriver depending on Gai's Explaination which the latter explain it to Yotagaki that his action is to control Ark by Manipulating it from Naki who was on Fuwa's head.

However, after hearing Gai's explaination to control Ark using Naki's AI Chip from Fuwa, Yotagaki is very disappointed at Gai as he told the latter that the Project Thouser will be frozen and will send back the Thousandriver as Yotagaki left Gai's office.

Upon hearing that, Gai suddenly stopped Yotagaki as he claimed that the latter doesn't have the rights to send back the Thousandriver, however his words makes Yotagaki to be even more disappointed and became angry at Gai as he explain that the latter himself and his arrogance are the reason that The Ark goes out of control for his own interests. He then told Gai that the latter doesn't need to be president after what he did to The Ark as Yotagaki left the office.

Yotagaki (while wearing ZAIA Spec) then met Naki (who took over Fuwa's body after they contact Gai) as the former told them about Gai's bad deeds that will destroy ZAIA Enterprise Japan's reputation but soon being held at gunpoint by Naki and he notices that his ZAIA Spec was hacked and became broken by Naki as they told him that they will obey Gai for The Ark's will. However, Yotagaki doubts their words and knew that Humagears are poorly liars as he ask Naki to kill him immediately if they obey Gai just for The Ark's will. He then ask Naki once again about pretending to obey Gai after the latter kill them with a revolver as Naki told him that they need the Thousandriver to defeat Ark as he was surprised and thinking that Ark is the leader of MetsubouJinrai.net, but Naki then told him that after they being with Fuwa and knew Ark is also the enemy of Humagear as they also disagree with the desire to kill humanity and want to be free as Yotagaki interested with their words and want them to explain more about it.

Later, Yotagaki contact the department and asking them to get him through the development as he told them good news about how to control Ark through the complicated way by forcing Ark out, however they can't touch it due to Ark is at the bottom of the lake at Daybreak Town but they can bring its to land by using MetsubouJinrai.net as they need a vassel to hold Ark that will be destroyed, as Yotagaki decide to lifted the freeze on Thousandriver and allowing Gai to use it in order to control Ark due to him knew that Gai will cause more troubles while forcing the Project Thouser forwards on his own but soon he demand Gai to success this time.

Yotagaki then met Yua Yaiba as he introduced himself to her and gave her a special mission to restore Horobi after everything is finished but he also told her to not let Gai know about the involvement from ZAIA Enterprise as he told the reason that she knows the problems that Gai caused as Yotagaki left the building. He then was contacted by Naki and thanked the former for his help as he told them that their cooperative relationship is not so mutually beneficial as he believed and was hoping for a bright future between ZAIA and Hiden but it was destroyed due to the Daybreak Town Accident. He then wants his hope in the Thousandriver to combine two powers into one power and in Humagears while also thanking Naki for their help, as Naki ask his help for their last request.

Rebuilding Jin

After Jin was destroyed in the battle by Aruto, Naki (took control of Fuwa's body again) then gave Yotagaki Jin's Humagear Memory, and want him to rebuilt Jin into his new body as they told him to entrust the future of the project to Jin, while also want him to reset their data and reprogram them as well in order to completely wipe out MetsubouJinrai.net and their activities temporarily. Yotagaki then asking Naki about their future after the project works and they're freed, with Naki responds that there's zero chance that they will be freed and hope they can reunited with Jin, Horobi, and Ikazuchi as the former hope for a miracle that will happen to them.

On the way back to the corporate company, he contacted the department again and told them that they will create a completely independent Humagear that won't rely on both Ark and Zea. This would result in him recovering and rebuilding Jin's body, giving him the ZAIA Slashriser and Burning Falcon Progrisekey. I'll Save the HumagearsAs Long As There's Malice

Replacing Gai

After Azu collected his data to revive Ark, Jin contacted and notified Yotagaki of the Ark's impending return. How Was MetsubouJinrai Created?

Now appointed as ZAIA Japan's new President & CEO, he had but one goal in mind: destroy Horobi. As Long As There's Malice

However, upon hearing Yua Yaiba's plea to put end the conflict and to have peace between humans and Humagears, he eventually orders the A.I.M.S. soldiers to spare the protesting Humagears. After the final battle between Aruto and Horobi, it is implied that Horobi is later rebuilt by Yotagaki into an advanced Humagear, just like Jin.

Eden's Paradise Incident

To be added

Later Disappearance

As Gai mentioned that Yotagaki was not seen in a few days, he asked Lyon Arkland if Yotagaki's disappearance did have a connection with Lyon's presence in Japan. Lyon answered that he had granted him a bonus leave, so that he could replace him as a CEO of ZAIA Japan. His current status is still unknown.


Williamson is shown to have dream and hope for a bright future during the joint cooperation between ZAIA Enterprise and Hiden Intelligence during his time as a member of Ark development team alongside with his junior Gai Amatsu but he knew everything changes as the Ark goes out of control due to Gai's arrogance that Gai himself did for his own interests makes him disliked Gai Amatsu ever since and even decide to suspend the Project Thouser and want to bring the Thousandriver back to ZAIA Enterprise before he decide to give one more chance to Gai.

After Gai failed on his ZAIA Japan's position for what he done, Williamson happily took over Gai's position without even listening to Gai's reasoning. Despite this, he is shown to have more positive traits in contrast and is more reactive to action, seeking to eliminate the Ark, Horobi, and other potentially dangerous Humagear.

Behind the Scenes


Williamson Yotogaki is portrayed by Tomomi Maruyama (丸山智己 Maruyama Tomomi).



Icon-zero-one.png Kamen Rider Zero-One
Kamen Riders
Soreo Hiden - Aruto Hiden - Isamu Fuwa - Yua Yaiba - Jin - Horobi - Ikazuchi - Naki - Gai Amatsu - Ark - S
Movie-exclusive: Soreo Hiden - S - Behru - Kamen Rider Abaddon - Izu - Lyon Arkland - Kamen Rider MetsubouJinrai (Jin, Horobi, Ikazuchi & Naki)
Stageshow-exclusive: Azu - Little Assassin
Hiden Zero-One Driver - A.I.M.S. Shotriser - MetsubouJinrai Forceriser - Zetsumeriser - ZAIA Thousandriver - Cycloneriser - Raidriser - ZAIA Slashriser - Ark Driver - Hiden Zero-Two Driver - Zetsumetsu Driver - Eden Driver - Abaddoriser - MetsubouJinrai Driver
Progrisekeys - Progrise Holder - Progrisekey Connector - Hiden Risephone - Rider Models
Attache Calibur - Attache Shotgun - Attache Arrow - Breaking Mammoth - Giger - Buaruku Sabers - Authorise Buster - Assault Grip - Thousand Jacker - Progrise Hopper Blade - ZAIA Spec - Knuckle Demolition - Nihon Ookaminotsume - Claw Assault - Horobi's Katana
Hiden Intelligence: Korenosuke Hiden - Soreo Hiden - Jun Fukuzoe - Sanzo Yamashita
Humagears: Izu - Shesta - Soreo Hiden - Wazu Nazotoku - Subaru - Hakase Bot - Fukkinhoukai Jiro
Legend Riders: Sougo Tokiwa - Geiz Myokoin - Woz - Tsukuyomi
Humans: Norio Uozumi - Go Sakurai - Satoshi Sakurai - Choichiro Ishizumi - Seiji Tazawa - Satō - Yuta Yomura - Isao - Shinya Owada - Ikkei Amatsu - Akane Tono
Humagears: Mageana - Ikkan Nigiro - Anna - Mashirochan - Dr. Omigoto - Z #5 - Delmo - Love-chan - Midori
A.I.s: Zea - Zat - Ai-chan - Thouser
Ark - Horobi - Naki - Jin - Ikazuchi - Little Assassin - Azu
Monsters: Berotha Magia - Kuehne Magia - Ekal Magia - Neohi Magia - Onycho Magia - Vicarya Magia - Gaeru Magia - Mammoth Magia - Dodo Magia - Arsino Magia
Footsoldiers: Trilobite Magia - Dodo Magia Chick - Battle Magia
Other Villains:
Finis - Will
Gai Amatsu - Williamson Yotagaki
ZAIA Spec Representatives: Rentaro Tachibana - Tatsumi Arayashiki - Naoto Ichimori - Takeshi Homura - Masamitsu Yuto
Other: Daiki Kyogoku - Makio Nodachi
A.I.M.S.: Isamu Fuwa - Yua Yaiba - Naki - Eida - Ono - Degawa - Shida - Eifuku - Ito
Monsters: Crushing Buffalo Raider - Splashing Whale Raider - Dynamaiting Lion Raider - Storming Penguin Raider - Scouting Panda Raider - Fighting Jackal Raider
Footsoldiers: Invading Horseshoe Crab Raiders
Lyon Arkland - Sold9 - Sold20 - Sold404
Monsters: Dire Wolf Sold Magia - Serval Tiger Sold Magia - Crushing Buffalo Sold Magia - Splashing Whale Sold Magia - Storming Penguin Sold Magia - Scouting Panda Sold Magia - Invading Horseshoe Crab Sold Magia
Footsoldiers: Solds
S - Behru - Buga - Mua - Lugo
Footsoldiers: Kamen Rider Abaddon
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