In the year 2021, the Devil of Mystery Diablo, who was sealed away in the Diablo Stamp, was released into the world. In the year 2071, 50 years from now, humanity has been enslaved by devils. Ryunosuke Momose, who transforms into Kamen Rider Century, travels to the year 2021 to defeat Diablo before he can gain the power to rule the world. Ikki Igarashi, Vice, and Touma Kamiyama join forces with Ryunosuke to prevent the uprising of a world soon to be dominated by devils.