A brilliant university student named Takeshi Hongo is kidnapped by the terrorist organization Shocker and forcibly transformed into a powerful cyborg soldier designated Hopper. Unlike the original story, Hongo undergoes complete mental conditioning and initially serves Shocker loyally. The organization orders him to eliminate two witnesses who have seen their operations: a journalist named Asuka Midorikawa and her fiancé Katsuhiko Yano. During the attack, Hongo’s suppressed humanity resurfaces when he sees falling snow, but Yano is killed by another Shocker soldier, Spider. Asuka discovers Hongo beside her fiancé’s body and blames him for the murder, beginning a conflicted pursuit of the man she once knew.

Hongo, now a traitor to Shocker, receives guidance from motorcycle shop owner Tobei Tachibana, who provides him with the Cyclone machine. After defeating Spider, Hongo encounters a shocking sight: Asuka is now accompanied by a man named Hayato Ichimonji, who is the spitting image of her deceased fiancé. Unbeknownst to Asuka, Yano’s body was recovered by Shocker and rebuilt as the second Hopper, programmed to destroy the original. As Ichimonji hunts Hongo, a separate narrative thread reveals that two terminally ill hospital patients, Haruhiko Mitamura and Miyoko Harada, were given a chance at life by Shocker and transformed into the Inhumanoids Cobra and Snake.

When the Bat Inhumanoid attempts to kidnap Asuka for conversion, Ichimonji’s feelings for her override his conditioning, causing him to turn against Shocker. The two Riders unite at Shocker’s island base, defeating Bat, Cobra, and Snake. Although Dr. Shinigami and the other Shocker executives escape to plan anew, Hongo and Ichimonji fully embrace their roles as Kamen Riders, vowing to destroy the organization once and for all. The film reimagines the classic origin with darker themes of identity, memory, and tragic romance, set against a contemporary Japanese urban landscape and Shocker’s hidden island facility.