Biography of Ryoma Sengoku/Kamen Rider Duke from Kamen Rider Gaim.
Past[]
Ryoma was one of several orphans raised in Yggdrasill's Zawame Child Care facility, which was a front by Yggdrasill to experiment on and raise children to serve as their future employees. As a teenager, Ryoma would become one of the Corporation's leading researchers in their study of the Helheim Forest and its encroachment onto Earth, creating various inventions that harnessed its power. Among the first things he designed for the Corporation were the Zakuro Lockseed and the Yomotsuhgeri Lockseed, the former of which was used in a test run by Kugai Kudo. However, the experiment went awry and Kugai was seemingly killed after activating it.
Later in life, Ryoma became one of the top members of Yggdrasill's R&D branch headed by Takatora Kureshima, which sought to create a way for humans to survive on Earth once Helheim took over. Ryoma and Takatora would quickly become friends, sharing similar visions for humanity's evolution, and under Takatora's oversight Ryoma would create a device capable of harnessing the power of the Lockseeds of Helheim to grant its user a transcendent form - the Sengoku Driver, named after himself. However, while Ryoma had once seen Takatora as an ideal king to lead humanity in a post-Helheim world, he gradually began to lose his respect for Takatora after hearing of his boss's selfless desire to save as many people as possible, rather than create a society dominated by a select few who had proven themselves the strongest. It was around this time that Ryoma brought in two new members to Yggdrasill's inner circle. One of these was Sid, a small time crook whom Ryoma had offered him a job within Yggdrasill as a Lockseed Dealer. The other was Yoko Minato, a corporate spy sent to infiltrate Yggdrasill who Ryoma had caught and instead offered her a spot in his inner circle as his assistant and bodyguard, which Yoko accepted.
Yoko reporting to Ryoma.
Yoko would later report to Ryoma with startling news - a a sapient lifeform, one who had embraced Helheim's power while still retaining its own mind, had been discovered in Helheim. Dubbing this lifeform an "Overlord Inves", Ryoma became further curious about the power Helheim offered and soon discovered the existence of the Forbidden Fruit of Helheim, which held the power to grant whoever obtained it godhood. Having by this point lost all his faith in Takatora as a worthy ruler, Ryoma instructed Yoko to keep this information secret from Takatora, as doing so would show him an alternative to Yggdrasill's "Project Ark", a secret plan to exterminate 6/7ths of humanity to deprive Helheim of livestock to be converted into Inves. Secretly, Project Ark was conceived of by Ryoma only as a way to grant him access to the full range of resources provided by Yggdrasill, which he intended to take for himself and use for his true plan.
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.
Beat Riders Arc[]
While Lock Dealer Sid distributed Lockseeds and Sengoku Drivers to the youths of Zawame City so they could be used by Yggdrasill as guinea pigs to test the inventions, and Takatora oversaw Yggdrasill's experiments with Helheim and attempts to contain the forest, Ryoma mostly remained in the background, closely monitoring the data gathered from the Beat Riders' usage of the Sengoku Drivers. He is first seen participating in a meeting via video call alongside Takatora, Sid and DJ Sagara to discuss the new developments now that Oren Pierre Alfonzo had gained a Sengoku Driver.
Ryoma would meet with Takatora again to discuss the increasing number of portals to Helheim that were popping up. During the meeting, Ryoma informed Takatora of the new, more advanced Driver he had created, which Takatora offered to test out himself.
Ryoma and Takatora were later alerted to the presence of the Armored Riders, who had all entered Helheim to gather Lockseeds for themselves. While Takatora went to go deal with the Armored Riders however, Yggdrasill's encampment became besieged by a wave of Elementary Inves. Luckily, Kamen Rider Gaim was nearby and fought off the Inves while Yggdrasill's researchers evacuated from the camp.
Kamen Rider × Kamen Rider Gaim & Wizard: The Fateful Sengoku Movie Battle[]
Ryoma appears at the very end of the movie, standing with Takatora and Yoko and handing Takatora the new Genesis Driver he had developed.
Yggdrasill Arc[]
Ryoma and the other New Generation Riders make their debut.
After Ryoji Hase ate a Helheim fruit and transformed into the Hekija Inves, Ryoma, Takatora, Yoko and Sid went out to deal with him. Arriving just as Kouta was trying desperately to reason with Hase to resist, the four all unveiled their new Genesis Drivers, which Ryoma had developed, and assumed their New Generation Rider forms. Sigurd, on Zangetsu's orders, destroys the Inves and killed Hase, leading an outraged Kouta to try to confront the Yggdrasill Riders before being taken down by a group of Kurokage Troopers.
After Kouta and Kaito Kumon were both captured by Yggdrasill's Kurokage Troopers, Ryoma has them brought to him and formally introduces himself. He reveals that the purpose for them being used as guinea pigs is to develop a way to harness the power of Helheim Forest and asks for their permission to continue using them to develop more powerful devices derived from Helheim. The two make an attempt to grab both of their Drivers, but are swiftly blocked by Yoko Minato. The two are later sent back to their cells, only to be rescued by DJ Sagara and Mitsuzane Kureshima. Following their escape, Ryoma discovered that they had also taken the Lemon Energy Lockseed and the Genesis Core slot. Intrigued, Ryoma exploited the opportunity to use the data gained from Kouta's use of them to improve the mass-produced Sengoku Drivers.
Ryoma before transforming into Duke and engaging Gaim and Baron.
When Mitsuzane betrayed Yggdrasill's plan to take back Kouta's Sengoku Driver, Ryoma, sensing an inner darkness to Mitchy, decides to cover for him and persuades Takatora that Mitsuzane's actions were all part of his plan to gather data. Afterwards, Ryoma analyzes the data gathered from Marika's fight with Gaim. He later chooses to test out his own Genesis Driver on Gaim and Baron, and easily defeats Jimber Lemon Gaim and Baron, apologizing for how much power he used on them as he is not used to fighting. His easy defeat of the two Riders leads him to conclude that Yoko is holding back the true power of her Genesis Driver, leading him to ponder what her true motives are.
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 Arc[]
Gaim and Baron later broke into Yggdrasill again to gather more answers, only to be confronted by Zangetsu Shin and Sigurd respectively. As Sigurd overpowered Baron, Ryoma appeared to interrupt their fight, and later brought them back to his laboratory where he revealed to Kaito the truth about Helheim Forest at the same time Takatora showed Kouta the truth about the forest, furthering explaining that the Yggdrasill Corporation is just a front to find a way to contain Helheim's encroachment. He also reveals to Kaito that the sacred tree from Mai's family shrine is actually from Helheim and not of their world, which is why Yggdrasill can use it to open up a crack. After Kaito proclaims that they should be ensuring that the strong survive rather than trying to protect the weak, an amused Ryoma reveals that he, Yoko and Sid share a similar mindset and welcomes Kaito into his inner circle.
Ryoma later sent Kaito to gain information on the Overlord Inves, stating to Yoko that he did so to keep him busy. Sid then asks Ryoma for permission to go terminate Kouta, believing he would be a hindrance for them in the long run. Ryoma gives Sid the go-ahead, commenting that it would be a great opportunity to test the limits of the Genesis Core. Sigurd initially overpowered Gaim, but after becoming Gaim Jimber Lemon Arms Kouta was able to defeat Sid, only for Mitsuzane to secretly intervene and summon an Inves to distract Kouta while Sid escaped.
Ryoma was later tasked by Takatora with finding a way to close cracks quicker to minimize their harm, something Ryoma deemed a futile effort. As Inves emerged from the portal, Kouta Kazuraba arrived to assist Yggdrasill in defeating the horde. It is then that Ryoma reveals to Kouta the truth of Yggdrasill's "Project Ark" plan, how they're producing one billion Sengoku Drivers to arm one seventh of humanity with so they can survive in Helheim's biosphere and how they plan to kill off the remaining six-sevenths in order to deny Helheim subjects to be turned into Inves, all in order to manipulate Kouta into sabotaging Yggdrasill's failsafes to contain Helheim. After the Inves are defeated, Kouta breaks off his alliance with Yggdrasill and steals Yoko's Peach Energy Lockseed before going to break into Yggdrasill's headquarters again.
After Kouta destroys the Scalar System, Ryoma, believing Kouta had help from someone inside Yggdrasill, contacts Mitsuzane and tasks him with locating the traitor. Mitsuzane eventually discovers that the traitor is DJ Sagara, and shares the information with the rest of Yggdrasill's inner circle. Mitsuzane also tells Takatora of the existence of the Over Lord Inves, which he learned from Kouta, but Takatora does not believe him. Deciding that Kouta has served his purpose and is now becoming a hindrance to their plans, Ryoma gives Sid instructions to take Kouta out. Sigurd manages to overpower Gaim as Jimber Cherry Arms, but Kouta is able to evade and escape him.
The Red and Blue Kikaider[]
Ryoma receives the Hakaider body from a colleague of his in the DARK organization, who had asked him to test it out. Transplanting his brain into the body of the robot, Ryoma-Hakaider goes out to test its capabilities and attacks Kamen Rider Knuckle, something which draws the attention of Kouta and Jiro. After Jiro activates his "Reboot" function, he becomes Kikaider and drives Hakaider off with help from Gaim Kachidoki Arms. Returning to his lab, Ryoma puts his brain back into his body, having become unnerved by the android's destructive influences on his personality, and speculates about what use Hakaider served to DARK.
Overlord Arc[]
Ryoma later discusses with Yoko and Sid the investigation into DJ Sagara, and how they have uncovered little information on him. It is then that DJ Sagara himself appears before them. The three ask Sagara why he helped Kouta, to which Sagara explains it was to level up the competition. Sagara then reveals to Ryoma that his theory about the Helheim Forest hasving appeared in Earth's past is true and that every time it appears a human is chosen to receive the Golden Fruit to decide the fate of mankind. Sagara then drops a hint that the Overlord Inves hold the key to obtaining it before disappearing.
After viewing the footage of Kaito's fight with Demushu, Ryoma decides that he is no longer needed for their plans, only for Yoko to ask that Kaito be given another chance. Surprised by Yoko's plea, Ryoma permits it and Yoko later gives Kaito a Genesis Driver. Around this time, Takatora also discovered the existence of the Overlords now that Demushu and Redyue had intervened in Helheim's invasion, causing him to realize that there was another way to save humanity that didn't involve culling the population. As Takatora had now discovered the truth and would no longer go along with their plans, Ryoma decided Takatora had served his purpose and that it was time for them to off him.
Duke and Sigurd defeat Zangetsu.
Takatora would later set a new path for Yggdrasill to save humanity based on the information he had of the Overlords, ordering his employees to find out more about them. After Takatora transformed into Zangetsu Shin and headed into the forest to search for them himself, Kamen Rider Duke and the other New Generation Riders appeared and revealed their treachery to him. Takatora ordered Mitsuzane to file a report against the three, only to discover Mitsuzane was in on their conspiracy as well. With Takatora shaken by the revelation of his longtime friend's betrayal, the New Generation Riders were able to overpower Takatora and knock him off a cliff, seemingly killing him.
Duke using the Master Intelligence System to cut off communication.
Upon their return however, Sid betrayed Ryoma and destroyed his crack lab, revealing his own desire to claim the Forbidden Fruit before escaping through the closing crack. Acting quickly, Ryoma informed Kouta, Kaito and Mitsuzane that Sid was now acting on his own to claim the Forbidden Fruit and sends them to go after him. Sid would not get far however, and after he confronted Rosyuo for possession of the Forbidden Fruit would wind up being crushed to death by him. At this same time, Demushu led a full invasion into Zawame City, leading Ryoma to transform into Kamen Rider Duke in preparation. Duke uses the city's Master Intelligence System and cut off all communications within the city except for him and his forces, and sends Yoko with a squad of Kurokage Troopers to go combat Demushu. As the forces of Helheim encroach on Yggdrasill Tower however, Ryoma exits the scene in a rocket and leaves the rest of the Riders and the civilians of Zawame at the mercy of Helheim. Shortly after, Ryoma contacts Yggdrasill's international branch as their leaders are discussing the developments that have arisen now that Helheim has taken over Zawame, and offers to bring them in on his plan to claim Yggdrasill's Forbidden Fruit. The executives refuse and in response Ryoma leaks all information about Project Ark to the public, causing a mass panic and wave of backlash against Yggdrasill from all across the globe.
Forbidden Fruit Arc[]
Ryoma surrendering.
With the focus drawn off him and onto Yggdrasill as a whole, Ryoma would return to Zawame after some time had passed and came across the Riders in a garage plotting their next move against the Overlords. Making his arrival known by dropping a comment mocking Takatora, Ryoma quickly drew the ire of Kouta, who transformed to attack him. Ryoma in turn transformed into Duke and did battle with Gaim until Baron and Knuckle joined the fight. Ryoma then detransforms and offers to help them in stopping the Overlords, revealing that he knows of several different secret pathways into Yggdrasill Tower (which the Overlords were using as their base of operations on Earth). Though the Riders are hesitant to trust him (especially Yoko, who was still hurt by his betrayal), they agree to his assistance.
Ryoma in his normal attire.
Ryoma leads the group to one of the secret pathways to Yggdrasill Tower situated outside Zawame. As they exit the city, they notice that the entrance is no longer guarded, which Ryoma comments is likely due to the fact that Inves have now appeared worldwide thanks to him sabotaging Yggdrasill's efforts to contain the Helheim Forest. Ryoma also deduces that Redyue has used her energy on Kouta as they reach the secret pathway. After entering the Tower and fighting their way through the Inves, Gaim and Duke reach where Redyue is holding the civilians of Zawame hostage in order to power the machine she constructed to resurrect the Overlord Queen, Rosyuo's wife, back to life. The two Riders engage Redyue, but after Redyue uses her powers to hypnotize Kouta, Duke takes the opportunity to leave. Duke heads to the room containing the Master Intelligence System, which he uses to access footage of all the events that have transpired since he left Zawame. Ryoma later meets up with the other Riders again and informs Kouta and Kaito that Mai is being held by Rosyuo, leading them to go to Helheim Forest to save her.
Ryoma examining Mai.
Following the deaths of the remaining Overlords, Ryoma returns to Team Gaim's garage, where he finds Mitsuzane and a passed out Mai. Mitchy pleads with Ryoma to help Mai, and Ryoma soon realizes that Mai is now carrying the Forbidden Fruit within her body. Taking her to an abandoned hospital, Ryoma and Mitsuzane examine Mai's body to find a way to extract the Golden Fruit without killing her. It is then that DJ Sagara appears before them and reveals to them that the Forbidden Fruit will only leave her body once she chooses a champion to receive it. He further reveals that his true identity is that of the manifestation of the consciousness of Helheim Forest itself, and that he has traveled to many different worlds to advance the evolution of their species by having Helheim absorb them, before disappearing. After Sagara disappears, Ryoma convinces Mitsuzane to go kill Kouta before he can claim the Forbidden Fruit from Mai, as he is the only one she would likely give it to. To carry out the task, Ryoma gives Mitsuzane the Yomotsuhegeri Lockseeds, one of his first inventions, a Lockseed which grants its user immense power at the cost of threatening their life. Mitchy then goes to deal with Kouta while Ryoma, who agreed to look after Mai, finds a way to remove the Forbidden Fruit from her.
After Mitchy returns having apparently killed Kouta, Ryoma informs him that the operation to remove the Forbidden Fruit is successful and is pleased to hear that Kouta is now seemingly dead. As Mitsuzane goes to check up on Mai, he finds her dead and Ryoma then reveals that the Forbidden Fruit had fused with her heart, thus he had to kill her in order to obtain it. A distraught and furious Mitsuzane attempts to transform into Zangetsu Shin to fight Ryoma, but Ryoma disables Mitsuzane's ability to transform by activating a kill switch he placed inside the Genesis Driver, in case he may ever have to duel another New Generation Rider. Ryoma then beats up Mitchy untransformed while mocking him for his foolishness, telling him he's nowhere near as smart as he thinks he is and is just child playing an adult's game. As Ryoma tries to strangle Mitchy, the Golden Fruit suddenly transforms into a apparition of Mai, who states that she forgives Mitchy before teleporting away. While Mitchy devolves into a sobbing wreck, a now crazed Ryoma starts maddeningly trying to find the location Mai teleported to with the Fruit. It is then that Kaito and Yoko arrive and discover in shock what Ryoma had done. The two attempt to transform using their Genesis Drivers but Ryoma disables them as well, leaving Yoko out of the battle and forcing Kaito to use his Sengoku Driver to become Baron in order to fight Ryoma.
Duke defeats Baron.
Transforming into Kamen Rider Duke, Ryoma easily beats down Kaito with the power of his superior Genesis Driver and knocks him out of his transformation. Ryoma then mocks Kaito for the infection he received from Helheim, but Kaito instead thinks back to all the struggles he endured that brought him to this point. Deciding to take a gamble, Kaito eats the Helheim Fruit and is transformed into a new Overlord Inves which he self-dubs "Lord Baron". Surprised that Kaito has managed to retain his mind even after fully becoming one with Helheim, Duke engages Kaito again only to be overwhelmed by Lord Baron's massive power. After being knocked out of his transformation, Ryoma gives Kaito a warning about abandoning his humanity before letting himself fall to his death, choosing to commit suicide rather than die at Lord Baron's hands.
Kamen Rider x Kamen Rider Drive & Gaim: Movie War Full Throttle[]
The professor's return.
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.
Kamen Rider Gaim: Final Stage[]
Ryoma Sengoku was one of the deceased Riders revived by Maja, the nemesis of DJ Sagara, as his servants to take over the world of the living. Kamen Rider Gaim Kiwami Arms showed up to stop Maja, but Kamen Rider Duke and the other Riders overwhelmed him and stole his powers, causing him to lose his memories.
Maja then leads the revived Riders in an invasion of Zawame City, where Duke and Sigurd battle Armored Riders Bravo and Gaim and easily defeat them. Before they can finish them off though, Zangetsu Shin and Ryugen appear and provide cover for them to escape. Duke and Sigurd would later fight the Kureshima brothers again, being destroyed by Ryugen and Zangetsu Shin respectively.
After Maja transformed into Kamen Rider Maja, Duke and all of the other Riders reappeared to do a roll call with Kouta as Gaim Kiwami Arms, having now regained his memories, and fight against the revived Over Lords Maja had summoned. Duke and Sigurd took on Grinsha and defeated him with a combined Rider Slash and Sonic Volley. After the battle, Duke and Sigurd would disappear to return to the afterlife.
Kamen Rider Drive Saga: Kamen Rider Brain[]
In Brain Roidmude's dream, Kamen Rider Duke was one of the Dark Riders who appeared as servants of Mu sent to fight Kamen Rider Brain.
Kamen Rider: Beyond Generations[]
Kamen Rider Duke was resurrected as a demon as part of the Devil Rider Corps. He acted as an enforcer for the demons who controlled the future in 2071. When the future George Karizaki sent Ryunosuke Momose back in time with the Cyclotron Driver, the Devil Rider Corps were sent to attack George's laboratory, but were fought off by Touma Kamiyama, Rintaro Shindo, Yuri, Vice, Daiji Igarashi and Sakura Igarashi using the Clone Rider system.