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Villain Overview

My brilliance... and research... are the only things of value. They are the truth of this world!
~ Ryoma Sengoku while being confronted by Kaito.
It's been a long time, my friend.
~ Mecha-Ryoma Sengoku's greeting to the Kureshima brothers.

Ryoma Sengoku is a researcher for the Yggdrasill Corporation who created the Sengoku and Genesis Drivers and one of the two main antagonists of Kamen Rider Gaim alongside Redyue. With his Genesis Driver, Ryoma has the ability to transform into Kamen Rider Duke by inserting the Lemon Energy Lockseed.

Ryoma works under Takatora Kureshima, the head of Yggdrasill's research and development branch, and is one of the members of the conspiracy behind "Project Ark", a plan to cull 6/7ths of the human population. Unbeknownst to Takatora, Ryoma is secretly plotting to overthrow him and to use the Helheim Forest situation to claim power for himself. His ultimate goal is to obtain the Forbidden Fruit of Helheim and use it to become a God.

Ryoma serves as a background antagonist in the "Beat Riders" arc, the main antagonist of the "Yggdrasill" and "Helheim" arcs and a major antagonist in the "Overlord" and "Forbidden Fruit" arcs. He later returns as the secondary antagonist of the Gaim portion of Movie War Full Throttle, having been revived as Mecha-Ryoma Sengoku by the Megahex collective to assist it in assimilating Earth and Helheim. Ryoma also appears as a supporting character in Kamen Rider Gaim Gaiden: Kamen Rider Zangetsu, the overarching antagonist in Kamen Rider Gaim Gaiden: Kamen Rider Baron, and the main protagonist of the V-Cinema film Kamen Rider Gaim Gaiden: Kamen Rider Duke.

He was portrayed by Tsunenori Aoki.


Ryoma was originally one the children raised in the Yggdrasill Corporation-run Zawame Child Care Facility, where he was conditioned to become a scientist for Yggdrasill. He would eventually become a leading member of its Scientific branch and later meet and become friends with Takatora Kureshima, head of Yggdrasill's R&D branch, with whom he worked on a way to preserve humanity for when the Helheim Forest would invade. Together, the two created and developed the Sengoku Drivers, which Ryoma named after himself. While Ryoma initially saw Takatora as an ideal king fit to lead a new world, upon hearing of his selfless desire to save as many people as possible, Ryoma, who believed it to be a futile effort, began secretly plotting to undermine him.

Yoko reporting to Ryoma.

When Ryoma received a report from his subordinate Yoko Minato of an image appearing to be the Overlord Inves Demushu, he neglected to tell Takatora about its discovery despite the pathway it offered to stopping Helheim due to Takatora's philosophy of putting humanity first.

He first appears in the "Beat Riders" arc, operating in the background to analyze the data gathered from the Sengoku Drivers Lock Dealer Sid distributed to the youths of Zawame City while his colleague Takatora works to conceal the existence of Helheim from the general public. He gains a more prominent role in the "Yggdrasill" arc as one of the four New Generation Riders of Yggdrasill alongside his assistant and bodyguard Yoko Minato, Takatora and Sid. It is revealed Ryoma is the one who created both the Sengoku and Genesis Drivers and hinted throughout that has his own agenda apart from Takatora. It is subsequently revealed in the "Helheim" arc that Ryoma leads a secret splinter faction within Yggdrasill and is keeping Takatora in the dark about much of the true nature of Helheim Forest. In the same arc he recruits both Kaito Kumon and Takatora's younger brother Mitsuzane Kureshima to his inner circle.

In the "Overlord" arc, Ryoma finally puts his plans into motion. After Takatora discovered the Over Lords, Ryoma decides to dispose of Takatora and leads a coup against him with the other New Generation Riders, seemingly killing him. He is then betrayed by Sid, only for Sid to be killed by Rosyuo shortly after escaping into the Helheim Forest. After the Overlord Inves intervene and launch an invasion of Earth, Ryoma chooses to exit the scene for the time being and departs from Zawame City, leaving the other Armored Riders to face the hordes Helheim. He would not reappear until halfway through the Forbidden Fruit arc, where he returns to Helheim and assists the Riders against the Overlords before trying to obtain the Forbidden Fruit for himself again.

Ryoma also has a prominent role in many of the Gaim Gaiden spin-off movies, where he is linked to the origins of many of the villains in those films. In Kamen Rider Gaim Gaiden: Kamen Rider Zangetsu Touka Akatsuki was experimented on and given power by a Lockseed that Ryoma invented, leading her to seek revenge against Yggdrasill. In Kamen Rider Gaim Gaiden: Kamen Rider Baron, he supplied Alfred with his Genesis Driver and used him as a pawn to test out the Dragon Fruit Lockseed. In his own focus film, Kamen Rider Gaim Gaiden: Kamen Rider Duke, Kugai Kudo was another person mutated due to an experiment gone wrong with one of the Lockseeds created by Ryoma. Since Kugai Kudo was also responsible for empowering Shura, the villain of Kamen Rider Gaim Gaiden: Kamen Rider Baron, this technically makes Ryoma partially responsible for the events of that film too.

Following the events of Kamen Rider Gaim, Ryoma would make a full return in the film Movie War Full Throttle where he is revived by the mechanical life-form Megahex as Mecha Ryoma Sengoku and finally settles his score with Takatora.


Though appearing outwardly friendly, Ryoma is in fact an egotistical sociopath motivated by a desire to use the Helheim Forest to become a god and rule over the world. Like the other members of Yggdrasil's inner circle, he treats the Beat Riders as nothing more than guinea pigs to test his inventions and stepping stones to advance his own agenda. Ryoma doesn't even care for the lives of his own allies, being perfectly willing to send them to their deaths to ensure his own survival, such as when he sent his own bodyguard Marika and a handful of Kurokage Troopers to hold off Demushu while he escaped. Though he possesses tremendous power as Kamen Rider Duke and is a fairly skilled fighter, Ryoma is very cowardly and prefers to only enter fights that are clearly in his favor. To maintain his advantage over the other New Generation Riders, Ryoma installed kill-switches in the Genesis Drivers to prevent them from being used against him.

In addition to being extremely intelligent, Ryoma is very prideful about himself and his inventions, viewing his creations and research as the only things of value and the only acceptable means for humanity to evolve. As such he is outraged whenever someone manages to obtain a powerful state that is not due to his inventions. Despite this, Ryoma is a very effective manipulator and was able to keep Takatora in the dark about Helheim's Over Lords as well as his splinter group, having usurped Takatora's leadership in Yggdrasill in all but name.



Armored Rider Duke

New Generation Rider Duke

New Generation Rider Duke Dragon Energy Arms


  • He was named after the Japanese historical figure Sakamoto Ryōma, with his surname being derived from the Japanese "Sengoku" period.
  • Ryoma's popularity led to him getting to star in his own V-Cinema movie Kamen Rider Gaim Gaiden: Kamen Rider Duke.
  • Despite the complex morality of the show, Gaim's head writer Gen Urobutchi has stated that Ryoma is "the most evil person in Gaim."

External Links


           Gaim logo.pngVillains

Beat Riders
Kaito Kumon | Mitsuzane Kureshima | Hideyasu Jonouchi | Ryoji Hase

Yggdrasill Corporation
Takatora Kureshima | Ryoma Sengoku | Lock Dealer Sid | Yoko Minato | Mitsuzane Kureshima | Oren Pierre Alfonzo | DJ Sagara | Kurokage Troopers

Helheim Forest
Inves: Byakko Inves | Shika Inves | Komori Inves | Inoshishi Inves | Seiryu Inves | Komori Inves (Mutant) | Kamikiri Inves | Hekija Inves | Lion Inves | Yagi Inves
Overlord Inves: Rosyuo | Redyue | Demushu | Dyudyuonshu | Grinsha | Shinmugurun | Lord Baron

Underground Empire Badan
Ren Aoi | Mogura-Roid | Combat-Roids


Bujin Gaim's Army
Kamen Rider Bujin Gaim | Pitcher Plant Monster

Megahex Collective
Megahex | Mecha-Ryoma Sengoku | Mecha-Kurokage Troopers | Mecha Inves | Lost Number Roidmudes

Grasshopper Monster | Kougane | Touka Akatsuki | Alfred | Kugai Kudo | Black Bodhi | Shura | Neo Baron | Masako Suzuka

           DriveOfficialLogo.png Villains

Executives: Freeze Roidmude | Heart Roidmude | Brain Roidmude | Medic Roidmude | Mashin Chaser | Roidmude 004 | Roidmude 006 | Gold Drive | Roidmude 089 | Revenger Roidmude | Angel Roidmude | Paradox Roidmude | Sigma Circular | Roidmude 5886
Advanced: Sword Roidmude | Tornado Roidmude | Paint Roidmude | Gunman Roidmude | Crush Roidmude | Volt Roidmude | Imitation Drive | Iron Roidmude | Voice Roidmude | Scooper Roidmude | Seeker Roidmude | Judge Roidmude | Open Roidmude | Cook Roidmude | Shoot Roidmude | Thief Roidmude | Cyberoid ZZZ
Reaper Legion: Roidmude 013 | Roidmude 015 | Roidmude 019 | Roidmude 021 | Roidmude 022 | Roidmude 028 | Roidmude 032 | Roidmude 034 | Roidmude 035 | Roidmude 041 | Roidmude 044 | Roidmude 045 | Roidmude 054 | Roidmude 059 | Roidmude 070 | Roidmude 075 | Roidmude 080 | Roidmude 081 | Roidmude 083 | Roidmude 092 | Roidmude 094 | Roidmude 100 | Roidmude 101 | Roidmude 104 | Roidmude 105
Cobra-Type Roidmudes: Roidmude 014 | Roidmude 031 | Roidmude 037 | Roidmude 038 | Roidmude 049 | Roidmude 052 | Roidmude 055 | Roidmude 057 | Roidmude 062 | Roidmude 063 | Roidmude 073 | Roidmude 074 | Roidmude 082 | Roidmude 085 | Roidmude 086
Spider-Type Roidmudes: Roidmude 012 | Roidmude 018 | Roidmude 020 | Roidmude 025 | Roidmude 036 | Roidmude 039 | Roidmude 042 | Roidmude 046 | Roidmude 047 | Roidmude 056 | Roidmude 060 | Roidmude 064 | Roidmude 078 | Roidmude 079 | Roidmude 084 | Roidmude 093 | Roidmude 097 | Roidmude 102
Bat-Type Roidmudes: Roidmude 011 | Roidmude 016 | Roidmude 026 | Roidmude 040 | Roidmude 048 | Roidmude 051 | Roidmude 053 | Roidmude 061 | Roidmude 066 | Roidmude 068 | Roidmude 069 | Roidmude 071 | Roidmude 076 | Roidmude 077 | Roidmude 087 | Roidmude 088 | Roidmude 095 | Roidmude 096 | Roidmude 098 | Roidmude 103 | Roidmude 107
Other: Lost Number Roidmudes | Future Roidmudes

Hajime Taga | Itsuro Negishi | Koichi Sakaki | Koya Nishihori | Kisaburo Sasamoto | Makoto Asamura | Matsutaro Okumura | Mitsuhide Nira | Reiko Nishihori | Shunsuke Kusaka | Takuro Mogi | Tenjuro Banno | Zoruku Tojo

Keisuke Okamura | Roidmude 012 | Roidmude 055

Great Leader of Shocker | Kyoichiro Kuroi | Kamen Rider 4 | Roidmude 089 | Hiruchameleon | Turtle Bazooka | Roidmude 016 | Roidmude 057 | Roidmude 076 | Arimammoth | Cheetahkatatsumeri | Kamen Rider Ouja | Kamen Rider Sasword | Kamen Rider Dark Kiva | Kamen Rider Baron

Kibaoni Army Corps
Kyuemon Izayoi | Hitokarage

Leader of Mu | Oogumo Great Leader | Cancer Zodiarts | Gremlin | Demushu | Gamma Superior | Guren Graphite | Kamen Rider Dark Kiva | Kamen Rider Wiseman | Kamen Rider Poseidon | Kamen Rider Duke | Kamen Rider Dark Ghost | Kamen Rider Another Para-DX

Megahex Collective
ZZZ Megahex | Mecha-Kaito Kumon | Lost Number Roidmudes

Da Vinci Gamma | Michelangelo Gamma | Raffaello Gamma | Gamma A

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Contract Holders: Ibata | Araki | Ayaka Oketani | Masao Honda | Amahiko Haitani | Seiko Omori | Mayu Tominaga
Footsoldiers: Giff Junior | Gifftarian | Hell Gifftarian
Giff Demons: Vail | Vice | Kagero
Others: Namio Yoshida | Judge | Hitoshi Maezono | Sword Roidmude | Heat Dopant | Shika Inves

Hideo Akaishi | Daiji Igarashi | George Karizaki | Akemi Mikoshiba


Agariyama | Masumi Karizaki | Shozo Irabu

Diablo | Himiko Crisper | Khufu Crisper | Edison Crisper | Leonidas Crisper
Devil Rider Corps: Shocker Rider 1 | Shocker Rider 2 | Kamen Rider Ouja | Kamen Rider Eternal | Kamen Rider Sorcerer | Kamen Rider Duke | Kamen Rider 4 | Kamen Rider Barlckxs

Zanjioh | Poison Lizard Man | Saboteguron | Shiomaneking | Scorpion Man | Ghoster | Jaguarman | Shocker Combatmen