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My brilliance... and research... are the only things of value. They are the truth of this world!
~ Ryoma Sengoku while being confronted by Kaito.

Ryoma Sengoku is a researcher for the Yggdrasill Corporation who created the Sengoku and Genesis Drivers and the main antagonist of Kamen Rider Gaim. 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. Unbeknownst to Takatora, Ryoma is secretly plotting to overthrow him and use the Helheim Forest situation to claim power for himself.

Ryoma later returns as the secondary antagonist of the Gaim portion of Movie War Full Throttle, having been revived 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, a background 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 among the children raised in the Yggdrasill Corporation-run Zawame Child Care Facility where he was conditioned to become a scientist for Yggdrasill, eventually becoming a leading member of its Scientific branch.

Ryoma would eventually meet and become friends with Takatora Kureshima, head of Yggdrasill's R&D branch. Together, the two created and developed the Sengoku Drivers, which Ryoma named after himself.

Yoko reporting to Ryoma.

Ryoma later 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 discover due to Takatora's philosophy of putting humanity first.

Beat Riders Saga


Ryoma in his normal attire.

Ryoma informed Takatora about the new Driver model, which Takatora offered to test the belt. Ryoma later attempted to get the 7 prototype Sengoku Drivers in the Helheim Forest. Though Takatora did not want any outsiders to be in the forest, Ryoma told Takatora to not destroy his precious work. During the Inves breakout of this event as they run rampant to Zawame City, Ryoma aids Gaim through the use of the Yggdrasill's tower through the use of a cloaking mechanism and beam weaponry.

Ryoma later created the Yomotsuheguri Lockseed in an attempt to harness more power from Helheim. However, after discovered that the Yomotsuheguri Lockseed drained the lifeforce of its user, Ryoma abandoned it. Ryoma also noted that the first Lockseed he created was dubbed the Ringo Lockseed which gives a potent amount of power that allows users to manipulate Cracks at will. However, the Ringo Lockseed overwhelmed its user by spouting Helheim vines from the Ride Wear. Ryoma also worked on a successor prototype of the Suika Lockseed dubbed the "Watermelon Lockseed" because the Suika Lockseeds were hard to come by and had to recharge. This Lockseed was scrapped due to the fact that the output of the Watermelon Lockseed was inferior to the newly created Energy Lockseeds and that the Watermelon Lockseed drains the stamina of the user much more quickly.

Kamen Rider Gaim Gaiden: Kamen Rider Duke


Ryoma and Takatora about to transform.

Yggdrasill fell under attack from Kugai Kudo and the Black Bodhi. Kudo had previously been a researcher for Yggdrasill who was sent into limbo after a test of the Zakuro Lockseed developed by Ryoma went wrong. Sending his brainwashed followers to suicide bomb Yggdrasill in order to test Ryoma, believing that with Ryoma's assistance he can become a god. Ryoma and Takatora later manage to unearth the location of Kudo's artificial Lockseed warehouse and go there to confront him. Transforming into Kamen Rider Duke, Ryoma battles Kudo as Armored Rider Saver, Ryoma manages to defeat him by damaging his Sengoku Driver, rendering him unable to maintain his physical form.

Yggdrasill Saga


Ryoma and the other New Generation Riders.

Ryoma had Takatora test the Genesis Driver, noting its impressive strength. Ryoma later watched Sigurd kill Ryoji Hase. Ryoma then introduced himself to Kouta and Kaito and asked for their permission to continue using them to complete his quest for power, but the two escape. Ryoma later discovered that the Genesis Core slot and the Lemon Energy Lockseed is stolen and pondered why someone would take an incomplete core slot prototype.

Ryoma used the data received from Kouta's Sengoku Driver to improve the mass-production models. He also examined the data from Jimber Lemon Gaim and Marika's fight and decided to test how his Genesis Driver would do on Kouta. Transforming in Kamen Rider Duke, Ryoma easily defeated both Jimber Lemon Gaim and Baron.

Ryoma later attempts to trick Kaito into finding the Over Lords without the equipment to combat them. Ryoma also apologized to Kaito for what Yggdrasill did to his family, by buying and destroying the construction factory Kaito's father owned.

Later, when a Crack appears on a bridge in Zawame City, Takatora sent Ryoma down to the other side of the Crack in the Helheim Forest. Ryoma later explains Kouta what Project Ark and Yggdrasill plans to reduce humanity 1 billion in order to eliminate the potential 6 billion Inves, as well as how the Sengoku Driver will help the remainder of humanity as it converts Helheim's fruits into Lockseeds and enables the wearer to absorb the nutrients safely without side effects. As the Crack closes, Kouta steals Yoko's Peach Energy Lockseed and rushes to HQ to destroy the Scalar System.

Kamen Rider Gaim Gaiden: Kamen Rider Zangetsu

Yggdrasill falls under attack from a mysterious Armored Rider capable of controlling the power of Helheim. From the Rider's power to create Cracks, Ryoma is able to identify the Lockseed it is using as the Ringo Lockseed, though he does not inform Takatora of this. As Takatora investigates the unknown Rider's origins, Ryoma gives him the Watermelon Lockseed to Takatora for him to use with his Sengoku Driver as a back up in case he loses his Genesis Driver.

The Armored Rider attacking Yggdrasill is later revealed to be Takatora's childhood friend Touka Akatsuki, who was raised and experimented on in Yggdrasill's Zawame Child Care facility. After Takatora defeats her and spares her life, Ryoma approaches Touka and reveals himself as another orphan raised in the facility before killing her to take the Ringo Lockseed back without Takatora knowing.

Kamen Rider Gaim Gaiden: Kamen Rider Baron

Ryoma Sengoku met with Alfred to discuss the purchase of Yggdrasill's Sengoku Drivers. However, Ryoma supplies him with a Genesis Driver and the prototype of the Dragon Fruits Energy Lockseed instead, plotting to use Alfred as a guinea pig to test the Lockseed out. After the Lockseed transformed Alfred into a pseudo Over Lord, Ryoma sent Yoko to give Kaito Kumon the Ringo Lockseed to test its strength. Baron Ringo Arms manages to destroy Alfred, but the Ringo Lockseed is also destroyed in the fight.

Helheim & Over Lord Saga

Ryoma later apologized to Mitsuzane for giving Kouta classified information. He realizes that Kouta is being supported by someone else when Kouta uses the Kachidoki Lockseed and tells Mitchy to find out who it is. Mitsuzane later informs him and along with the other Yggdrasill employees of creatures even more dangerous to humanity than the Inves. Realizing that their chance for power is dwindling, Ryoma provides Sid with another Cherry Energy Lockseed, so as to give Sid a chance to kill Kouta.

DJ Sagara later and Ryoma tells him about how the history of Helheim and how it has affected human civilization, before disappearing after instructing them to find the Overlords.

Seeing that the Sengoku Driver isn't a match against an Overlord, Ryoma let's go of Kaito from his group. However, Yoko gives Kaito a Genesis Driver replacement to provide him with another chance. When figuring out how to find the Over Lords, Mitsuzane tells them that they can easily find the Over Lords if they adhere to his plans.

20141223123918!Duke Lemon Shoot

Duke and Sigurd defeat Zangetsu.

After Takatora discovered the Over Lords, Ryoma attempts to dispose of Takatora and transforms into New Generation Rider Duke. Ryoma defeats Takatora, with Sid throwing him off a cliff. They later go to Yggdrasill's headquarters and erase all of Takatora's records.

Screen Shot 2014-12-29 at 8.45.55 PM

Duke using the Master Intelligence System to cut off communication.

However, Sid destroys all of the equipment around the tree, causing the Headquarter's Crack to disappear and close. Ryoma then tells Kouta, Kaito, and Mitsuzane to stop Sid from getting the Forbidden Fruit. When Demushu attacks Zawame City, Duke cuts off all communication in the city save the forces fighting Demushu. When Helheim's plants begin to absorb Yggdrasill Tower, Duke abandons Marika and the other Yggdrasill employees and escapes in a rocket, causing him to lose Marika's loyalty.

Forbidden Fruit Saga

Ryoma later attends a holographic conference between the executives of Yggdrasill's international branches. The executives threaten to arrest him due to the Japanese branch's responsibility disaster, but Ryoma uses a bug in the executives' phones to expose Project Ark and Yggdrasill's plans to cull the population to the world, sparking a global panic.

Ryoma then goes back to Zawame. He meets Kouta in Team Gaim's garage and mocks him about Takatora fate, provoking a fight between the two. However Armored Riders Knuckle and Baron appear and ambush him. Ryoma surrenders and reveals to the alliance of a secret entrance to Yggdrasill Tower before leaving them.

Screen Shot 2014-07-20 at 9.10.10 pm

Ryoma surrendering.

While Oren and Hideyasu fight the Inves, Ryoma and Kouta enter Yggdrasill Tower. However, they are confronted by Shinmugurun. Kouta fights the Overlord, but isn't able to defeat it. Duke steps in and takes down Shinmugurun easily. However, he doesn't kill him to see to collect data on the Gaim Kiwami Arms. After the battle is over, he makes a thought that it will be interesting to collect more data about Kouta's new power.

Arriving on the site where the kidnapped citizens are, Ryoma leaves Gaim to fight Redyue. Ryoma then reboots the Master Intelligence System to access records prior the Inves invasion. Upon discovering Rosyuo's name while analyzing the footage, he theorizes that the White Over Lord is the one holding the Forbidden Fruit.

Kamen Rider Duke 05

Ryoma examining Mai.

Ryoma later secretly follows Kouta and Kaito to gather data of Rosyuo's power in Helheim. Despite the Forbidden Fruit from Rosyuo expiring, Ryoma discovers that Rosyuo planted a second Forbidden Fruit in Mai. Ryoma returns to Zawame and forms an alliance with Mitsuzane to extract the fruit. They bring Mai to a hospital where Ryoma examines her body. Sagara then appears, explains his purpose to them before disappearing again. Ryoma informs Mitchy that he can remove the fruit from Mai, but states that Kouta would interfere and gives Mitchy the Yomotsuheguri Lockseed to defeat Kouta with. Ryoma also warns Mitsuzane the consequences of using it before he leaves.

Later, Mitsuzane returns and Ryoma states that he did not expect Mitsuzane to survive. Ryoma reveals to Mitchy that the Forbidden Fruit had fused with Mai's heart and, in order dissect it, Ryoma had to kill her. Enraged, Mitsuzane tries to attack him, but Ryoma disables his Genesis Driver. However, the Fruit turns into an apparition of Mai and disappears.

Kamen Rider Duke 08

Duke defeats Baron.

Ryoma attempts to locate where to fruit is, but he is confronted by Kaito and Yoko, who sought to avenge Mai. Ryoma disables their Genesis Drivers, forcing Kaito to use his Sengoku Driver instead. Because the Sengoku Driver is weaker than the Genesis Driver, Duke defeats him.

However, Kaito consumes a Helheim Fruit, changing him into an Over Lord Inves called Lord Baron. Ryoma attempts to fight Lord Baron but Lord baron easily defeats him. Before Lord Baron can kill him, Ryoma tells Kaito that he won't survive long and falls off the edge the off the building they're on, causing him to plummet to his death.

Movie War Full Throttle


The professor's return.

It's been a long time, my friend.
~ Mecha Ryoma's greeting to the Kureshima brothers.

Ryoma returns in the film Movie War Full Throttle when he's revived by the mechanical life-form Megahex as Mecha Ryoma Sengoku. Declaring that by becoming one with Megahex he has become equal to a god, Mecha Ryoma equips the Dragon Fruits Energy Lockseed to transform into Kamen Rider Duke and attacks the two Kureshima brothers, swiftly beating them down and forcing them to retreat.

Later the brothers face off against Ryoma again when they return to save Mai from Megahex. While Mitsuzane goes to rescue Mai, Mecha Ryoma fights Takatora in a decisive battle. Takatora uses his Musou Saber to stab through Ryoma's Genetic Ride Wear and kill him. Mecha Ryoma said his last words to Takatora before dying. His Genesis Driver was promptly taken by Takatora to allow him to transform into Kamen Rider Zangetsu Shin again.


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.




  • 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."


           Gaim logoVillains

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
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

Kougane | Kamen Rider Bujin Gaim | Pitcher Plant Monster | Bujin Gaim's Army | Megahex | Touka Akatsuki | Alfred | Kugai Kudo | Black Bodhi | Shura | Neo Baron

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

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