Ryoma Sengoku is a central character in the tokusatsu series Kamen Rider Gaim. As a brilliant scientist and the head of the Yggdrasill Corporation's research division, he is the creator of the Sengoku Drivers, Lockseeds, and much of the Rider technology. Transforming into Kamen Rider Duke, Ryoma is an ambitious and manipulative individual whose actions and inventions significantly affect the series' plot. He serves as both antagonist and complex figure, challenging the main characters intellectually and morally.