Kamen Rider Decade: All Riders vs. Dai-Shocker

The Hikari Studio arrives in a new AR World, and Tsukasa's photos make it seem like they may be in his home world. Natsumi wonders if the world is connected to Tsukasa's own reality. Tsukasa recalls the mansion that appears in the backdrop, hinting at a familiar place. They meet a girl named Sayo who immediately identifies Tsukasa as her older brother.

Sayo confirms Tsukasa is her brother, while Tsukasa reveals he has lost most of his memories. Nobuhiko Tsukikage arrives and confronts him about leaving his sister for a year. The past actions loom over them, creating tension and questions about loyalty and duty.

Tsukikage explains that Tsukasa's journey has unlocked a possible solution to the Nine Worlds crisis: a contest to determine the strongest Kamen Rider, known as the Rider Battle. The fusion of Nine Worlds continues to threaten the World of Decade. Tsukasa's memories begin to return as the plan takes shape.

Three days after the plan is revealed, multiple matches lead to a climactic six-man tag battle. The Decade team faces V3, BLACK, and Super-1 with Kuuga and Diend at his side. Diend and Kuuga are overwhelmed, forcing Decade to stand alone and win the fight.

Following Decade's victory, a castle rises from the stadium and Natsumi and Yusuke find themselves in a throne room. They are greeted by Dai-Shocker as Eijiro reveals himself to be Doctor Shinigami, toasting Tsukasa's return. The ominous scene signals a larger plan to conquer the saved worlds.

Tsukikage declares his loyalty to Dai-Shocker, while Sayo aligns with him. The two reveal their roles in the plot, and Tsukikage's scheme drives him to take the form of Shadow Moon. Sayo uses her Stone of the Earth on Yusuke, unleashing Kuuga's greatest power within him.

Natsumi and Yusuke escape to the Kadoya mansion, where they begin to uncover Tsukasa's childhood with Sayo's help. They learn that Sayo and Tsukikage are allied with Dai-Shocker. The conspiracy deepens as the truth about their connections comes to light.

Sayo uses the Stone of the Earth on Yusuke, unleashing Kuuga's most dangerous power within him. Natsumi watches in alarm as the controlled power threatens to overwhelm Yusuke. The scene underscores how fragile the balance of power has become.

As Dai-Shocker attacks across the worlds, Narutaki saves Natsumi and they encounter Daiki disguised among the invading soldiers. Narutaki sees hope in Daiki's ability to travel between worlds and proposes gathering the Kamen Riders to stand against Dai-Shocker.

Jōji Yūki confronts Tsukasa to avenge his lost arm, but realizes Tsukasa has changed and becomes a target for Dai-Shocker. Yūki sacrifices his robotic arm to allow Tsukasa to escape as he begins his transformation into Riderman.

Diend and Natsumi are attacked by a Dai-Shocker platoon. Diend summons Raia, Gai, and Punch Hopper to distract the enemies, then flees with Natsumi as Tsukasa arrives to help. They manage to drive off Jark and escape together.

The other Riders arrive to assist Decade in the assault on Dai-Shocker's forces. Kamen Rider W defeats Shadow Moon, pinning him in the castle, and the Riders combine to destroy the Dai-Shocker castle.

The shock of victory awakens King Dark as Diend arrives with Kamen Rider J. Using the DecaDriver Final FormRide card, Decade is turned into Jumbo DecaDriver, which transforms J into Decade Complete Form Jumbo Formation and delivers a Dimension Kick to defeat King Dark.

After parting ways with the Riders, Tsukasa makes amends with Sayo and begins his true journey within the Hikari Studio, his true home. Eijiro reappears as if nothing happened, leaving the door open for future twists. Natsumi and Yusuke’s paths diverge as the worlds settle into a fragile peace.