After obtaining the refined T2 Gaia Memories from a fellow Foundation X agent, Jun Kazu, Tabata [Tsunekichi Ōmori] leaves Futo by helicopter to a hidden base, not realizing he is tailed by a Hercules cargo plane. In a dramatic leap, a young man [Masaki Suda] jumps from the aircraft into the helicopter, seizing the briefing case and the E memory to transform into a caped Kamen Rider. Tabata detonates the suitcase, surviving the blast that tears the helicopter apart, and the rider lands back in the cargo plane where accomplices await as the rain of 25 more T2 Gaia Memories begins to pepper Futo. The ominous plan is clear: the group’s leader intends to turn the city itself into hell on Earth, using memory-powered power to rewrite the rules of their world.
Sometime later, the city’s rain delays the planned Futo Fireworks festival as Philip sits in a park near the Gaia Library, absorbed in a book and quietly absorbing the mood around him. He notices a mother with her son, Eita [Shion Sato], and a quiet ache stirs in him, recalling a recent encounter with Shroud and the complexities of family bonds. A sudden clash erupts nearby as IceAge and Violence Dopants attack unsuspectingly, their Gaia Memories still dangerous even after past destructions. Philip holds the threat at bay with unexpected support from a mysterious woman who reminds him of Shroud, and then Shotaro [Renn Kiriyama] arrives to join the fray. Together, the pair fuse into Kamen Rider Double to tackle the IceAge and Violence Dopants, while Kamen Rider Accel steps in to defeat Nasca and Weather, confirming—at least in this moment—that their designs share a common thread with the fight at hand. The battlefield takes on a surreal energy as a mysterious green Dopant intervenes to save the mother and child from falling debris, and the Joker’s Strange Maximum Drive completes the sequence of events that pushes the confrontation to a new threshold.
The two Dopants reveal themselves to be Watcherman and Santa-chan, who had found the Gaia Memories forcefully entering their bodies before a charismatic woman returns and introduces herself as Maria S. Cranberry, an Interpol agent. Back at the Narumi Agency, Maria explains that the Gaia Memories are T2 variants—refined versions of the earlier T1 designs—and that the city’s rain of memories is the work of a terrorist faction led by Katsumi Daido. Philip grows curious about Maria, who he suspects might be Shroud, and a thread of personal tension pulls him toward discovering the truth as he discovers a music box that feels connected to her.
On the surveillance front, Shotaro heads to consult his informants Queen and Elizabeth. Elizabeth reveals that the team has found T2 Memories for Accel, Key, and Bird, while Queen adds that the T2 Queen Memory has surfaced and is slipping into the street. A female motorcyclist, Reika Hanehara [Minase Yashiro], picks up the Queen Memory, and when she emerges wielding the T2 Heat Memory and transforming into the Heat Dopant, Shotaro pursues in the HardBoilder. It turns out to be a trap, as Kyosui Izumi—further revealed as the Luna Dopant—uses the T2 Luna Memory to summon Masquerade Dopants. Double fends off the Dopants but is ultimately forced to withdraw, and a mysterious green Dopant appears once more to spirit him to safety. At the agency, Philip uses the Gaia Library to confirm that NEVER, short for Necro-Over, or undead super soldiers developed by Foundation X, is behind the plot—along with nineteen of the T2 Gaia Memories that have been recovered.
Amid the tremors of fear and uncertainty, Daido’s plan intensifies. A trap is sprung when Daido transforms into Kamen Rider Eternal, claiming the right to be a true Rider and unleashing a brutal assault on Shotaro and Philip as they fuse into Double FangJoker, while Ryu as Accel battles NEVER’s sniper Ken Ashihara and uses the T2 Trigger Memory to become the Trigger Dopant. Even the combined power of CycloneJokerXtreme seems unable to hold Eternal’s relentless onslaught, as Eternal activates the Eternal Requiem Maximum Drive, negating all non-T2 Gaia Memories and leaving the others powerless. In a desperate move, Maria reveals a breakthrough: the Cyclone Memory is a tool she can use to become the green Dopant, and she begins handing Eternal their own T2 Gaia Memories to NEVER while delivering a crucial message to Philip.
The situation deteriorates rapidly as NEVER completes the transformation of Futo Tower into their operational base, unveiling their ultimate weapon—the X-Bicker. The next day, the group hides in a forest, nursing wounds and piecing together a plan as Ryu picks up a broadcast on his Beetle Phone announcing NEVER’s million-yen bounty for the final missing T2 Gaia Memory, the J Memory. The lure of the reward triggers a city-wide scramble, and a fissure forms between Shotaro and Philip over whether Maria can still be trusted. Philip, driven by a longing for truth and family, finds Maria at a music hall and confronts her, only for Daido to reveal that Maria is his mother and to knock Philip out, shattering his certainty.
Back at the agency, Shotaro confronts the implications of Philip’s turmoil when Kamen Rider Skull appears in the office, helping him realize that Philip’s yearning for family is a human core of vulnerability that fuels their mission. Reika returns, intent on finishing the fight, transforming again into the Heat Dopant and launching a fierce assault that reveals a hidden hole in the ceiling and the presence of the T2 Joker Memory. Shotaro seizes the moment, transforms into Kamen Rider Joker, and rushes toward the creek to bring the fight away from innocent civilians, delivering a decisive Rider Kick Maximum Drive that knocks out the Heat Dopant. With Ryu’s Engine Blade at his side, he makes his way to Futo Tower to rescue Philip, drawing Luna Dopant’s attention as the Masquerade Dopants strike at him with illusory attacks.
Inside the tower, Joker battles the Metal Dopant and uses the Rider Punch Maximum Drive to break through. Philip is strapped to the X-Bicker as Eternal’s energy surge threatens to vaporize the city. Eternal’s power climbs as he absorbs the X-Bicker energy and prepares to unleash a catastrophic strike. But the city’s support coalesces around Double, the Xtreme upgrades surge under the pressure, and CycloneJokerXtreme evolves into CycloneJokerGoldXtreme, granting Philip and Shotaro the chance to strike back. Double charges Eternal at the tower’s summit, delivering a final Golden Xtreme Maximum Drive Rider Kick that pierces Eternal’s defenses and destroys the Eternal Memory. Katsumi Daido’s laughter fades as the cataclysm of the explosion rocks the skyline, his own power finally ending in a spectacular blaze, while the Eternal Memory collapses into dust.
In the aftermath, the city begins to heal, fireworks illuminate the night, and repairs to Futo Tower start as the surviving allies celebrate the victory over NEVER. The post-battle calm is briefly interrupted by a mysterious figure in bandages shown in a bathroom after the credits, hinting at new stories to come.
Throughout this sprawling conflict, the film intertwines themes of memory, responsibility, and found family, balancing undercover operations, heroic battles, and personal revelations with a steady, grounded tone that leaves room for hope even as the city rebuilds. The spectacle is matched by character moments—Philip’s quest for truth, Shotaro’s loyalty to his partner, Maria’s conflicted allegiance, and Daido’s ruthless ambition—creating a cinematic tapestry that remains faithful to its roots while expanding the Kamen Rider universe in bold, interconnected ways.
