The film begins during a high-jacking of a passenger plane by a rogue extremist group named A.Z., led by the tyrannical Azuma, who seeks to plunge humanity into chaos and establish a new world order. On board the flight are Daiji and Sakura Igarashi, who quickly transform into Kamen Riders Live and Jeanne to combat the hijackers. However, Azuma proves to be overwhelmingly powerful, easily neutralizing the siblings and capturing the remaining passengers, including their parents, Junpei and Yukimi, alongside numerous innocent civilians. The plane is diverted and crashes onto a mysterious,
isolated island facility that once served as a base for the sinister organization Deadmans.Meanwhile, Ikki Igarashi, the eldest brother and primary host to the inner demon Vice, receives word of the hijacking and immediately rushes to rescue his family. Unbeknownst to him, Azuma’s master plan involves utilizing the captive Igarashi parents. Azuma harbors a deep, twisted grudge against Giff, the
cosmic entity worshiped by the Deadmans, and anyone connected to the lineage of the Revice system. Azuma was once a brilliant scientist and a prototype warrior who was discarded and left to rot, driving him to madness. He intends to use the life force of the Igarashi parents—whose genetic makeup is uniquely tied to Giff—to activate an apocalyptic device called the Giffard Engine, which will permanently strip all of humanity of their inner demons and reduce them to docile, lifeless husks under his absolute control.Upon arriving at the island, Ikki faces relentless hordes of modified grunts and formidable lieutenants. Despite the staggering odds, he is soon joined by fierce allies, including George Karizaki and former foes turned friends, who rally together to breach the facility's impenetrable core. Inside the fortress, the psychological stakes rise as Azuma forces the Igarashi siblings to confront their inner fears and the heavy burdens of their heroic destinies. The emotional core of the narrative intensifies when Azuma successfully activates the Giffard Engine, placing the parents in mortal peril and pushing the siblings to their absolute limits.Driven by a desperate desire to protect their family and humanity, Ikki, Daiji, and Sakura pool their inner strengths together. Unlocking a miraculous new evolutionary phase, Ikki and Vice achieve the ultimate Revice form powered by the Giffard Rex Vistamp. A cataclysmic final battle ensues across the island's crumbling ruins, culminating in a brutal clash against Azuma in his monstrous ultimate form. Through sheer teamwork, unbreakable familial bonds, and a definitive finishing blow, the Igarashi siblings shatter Azuma's machine, liberate their parents, and save humanity from total eradication, restoring peace to the world once more.