Four years after an alternate ending to the television series, the final battle of the Battle Fight has concluded with Kazuma Kenzaki, as Kamen Rider Blade, sealing away Hajime Aikawa, the Joker Undead. With the Joker defeated and all Undead seemingly imprisoned, the world has moved on. Kenzaki now works an unassuming job as a garbage collector, Mutsuki Kamijo has graduated high school, and Kotaro Shirai has found success as a published author. However, a new crisis emerges when the Undead begin to reappear, unsealed by a mysterious white version of the Joker known as the Albino Joker.

Without the ability to transform, Kenzaki is saved by a trio of new generation Riders: Kamen Rider Glaive, Kamen Rider Lance, and Kamen Rider Larc. These three artificial Riders were developed by the new BOARD organization, now led by former Rider Sakuya Tachibana, who has become the company's chief. After Kenzaki and Mutsuki, who regains the power to become Kamen Rider Leangle, help the new Riders reseal the escaped Undead, it is revealed that the seemingly helpful Kamen Rider Glaive is actually the Albino Joker in disguise. His goal is to obtain the ultimate power by sacrificing Amane Kurihara, a young girl who was close to the original Hajime, by sealing her within a special Vanity Card.

To save Amane, Kenzaki convinces Mutsuki to unseal Hajime from the Joker Card, bringing back Kamen Rider Chalice. The four original Riders unite to stop the Albino Joker, but they are too late to prevent the sacrifice, which summons a colossal, near-invincible monster named Jashin Fourteen. Realizing that Amane is the power source for the monster, Hajime leads Kenzaki to a secret location and reveals that a life must be exchanged to free her. Intending to sacrifice himself to save Amane and allow Kenzaki to defeat Jashin Fourteen, Hajime has a change of heart at the last moment and instead pushes Kenzaki out of the way, offering his own life in place of the girl's. Accepting his fate without fear, Hajime is sealed away by Blade once more, which weakens Jashin Fourteen enough for Kenzaki to assume King Form and destroy the monster and the Albino Joker. In the aftermath, Kenzaki assures a grieving Amane that Hajime's spirit will always be watching over her.