Kamen Rider × Kamen Rider W & Decade: Movie War 2010

Kamen Rider × Kamen Rider W & Decade: Movie War 2010 (仮面ライダー×仮面ライダー Ｗ（ダブル）＆ディケイド MOVIE大戦2010 Kamen Raidā × Kamen Raidā: Daburu ando Dikeido Mūbī Taisen Nisenjū) is the first annual Movie War crossover film that serves as the epilogue to Kamen Rider Decade and a prologue/flashback to Kamen Rider W, and was released theatrically on December 12, 2009. It features the last appearance of all of the A.R. World Kamen Riders that appeared in Kamen Rider Decade.

Plot
Accepting his fate as the destroyer of Worlds, Tsukasa has been fighting Kamen Riders, carding the search group of Skyrider, Super-1, and Kabuto, before running into a group of Riotroopers under Yusuke. Elsewhere, Daiki Kaito visits the Hikari Studio, convincing Natsumi to destroy Tsukasa's camera and photos, as they are only bittersweet memories of what used to be. By then, Decade's fight with Kamen Rider J enters their dimension as he uses Kamen Rider G4's Gigant and the Side Basshar to card J. Confronted by the Riotroopers, a young girl named Yuriko Misaki arrives and becomes Electro-Wave Human Tackle to take down the Riotroopers. She follows Tsukasa as he runs into Natsumi and Yusuke, who intends to stop Decade regardless of his injuries from the aftermath of Kamen Rider J's destruction. After explaining that he merely accepted his mission, Natsumi wants Tsukasa to remember who he was. However, Tsukasa throws his camera because he has no memories of Natsumi then fled. Natsumi feels powerless until Kiva-la arrives to remind Natsumi of Narutaki's words that only she can defeat Decade, offering her power to ensure it. Meanwhile in another part of this A.R. World, Eijiro Hikari visits a roadside food stand waiting for his friend "Ryu" when he is served a squid and a beer by Narutaki. This triggers a lost memory, resulting in his forced transformation into Super Doctor Shinigami. With Narutaki becoming Colonel Zol, he and Super Shinigami form Super Shocker from the remaining members of Dai-Shocker as they intend to take advantage of the dwindling number of Kamen Riders with the Neo Organism. Confronting Tsukasa at a warehouse, Daiki reveals that Yuriko was killed by Dai-Shocker's Bee Woman years ago, but Yuriko refuses to accept it as Kamen Riders Ryuki and Blade arrive. Using his Final Form Ride on Blade, Decade defeats Ryuki and then Blade as Yusuke arrives. Becoming Ultimate Kuuga, he battles Decade with the intent on killing him by becoming the Ultimate Kuuga Gouram to attempt a suicide attack before being defeated. Arriving, Natsumi uses Kiva-la to transform into Kamen Rider Kiva-la to fight Decade, only to be shocked when he allows her to run him through his Decadriver. He then gives Natsumi the Rider Cards, asking her to remember them before he dies. Daiki arrives as he and Natsumi are teleported to Wataru Kurenai, who reveals that Decade's roles as the destroyer and the connector have been fulfilled, restoring all of the A.R. Worlds, stating that their "stories" have been restored because by Decade fighting and destroying them, he created memories that allowed their stories to continue. Natsumi asks about Tsukasa, Wataru says that Decade has no story and no longer has an existence as he served his purpose. Natsumi and Daiki return to her reality and decide to try to bring Tsukasa back, only that Tsukasa never took a picture of himself. But when Natsumi remembers the photo she took of Tsukasa, they try to find his camera when Super Shocker arrives to bring Natsumi to Super Shinigami; Daiki and Yusuke hold off the Army to allow Natsumi to find the camera before being ambushed by the Bee Woman as Tackle arrives to drive off the Inhumanoid with her risky Ultra Cyclone attack before fading away. Wounded, the Bee Woman limps back to Super Shocker's base where she releases the Neo Organism, only to be consumed by it as it creates Doras to Super Shinigami's horror.

Natsumi tries to develop the photographs, but the camera was in such bad shape that Tsukasa's face does not appear. She holds it up, passing it to Daiki and Yusuke who also refuse to forget him. This act, as well as the other Nine Worlds' Kamen Riders, restores the photo as memories of Tsukasa represented by photographs manifest and merge, bringing Tsukasa back to life. By then, Super Crisis Fortress takes off as the Tsukasa, Yusuke, Daiki, and Natsumi arrive and assume their Rider forms to take out Colonel Zol's army, forcing the villain back to his usual self. However, Doras arrives as Narutaki curses Decade for causing this new turn of events. The Nine Worlds' Kamen Riders arrive to support them, but the fight is still to Doras's advantage until Decade assumes Complete Form while having most of the Nine Riders assume their ultimate forms (Kuuga Rising Ultimate, Agito Shining Form, Ryuki Survive, Faiz Blaster Form, Blade King Form, Armed Hibiki, Kabuto Hyper Form, Den-O Super Climax Form, and Kiva Emperor Form), and together destroy Doras with an all-out attack. However, wanting to play more, the Neo Organism sends out a mammoth robot to attack the Riders.

After the Mammoth Mecha is dropped, Decade survives the attack and gets on the Machine Decader as he is chased by the Neo Organism-possessed Super Crisis Fortress as Kamen Rider Double pursues the Dummy Dopant in his Dummy Wheel form on the HardBoilder. Within moments, the two Rider's battles intermingle as Decade and Double recognize each other and join forces as the other Kamen Riders join in the battle. Decade uses the All Riders Final Form Ride Card to transform the Nine Worlds' Kamen Riders into their Final Form Ride Forms to support Diend and Kiva-la as Double gets the Dummy Dopant off the Mammoth Mecha and convert it into the HardMammother to take down the Super Crisis Fortress while Decade chases after the Dummy Dopant. As Double manages to destroy the Super Crisis Fortress at the expense of the HardMammother, Super Shinigami tries to escape when the ShinigamiHakase Memory, which was given by Ryubee Sonozaki who was called "Ryu" by Eijiro himself, falls out of his neck, turning him back into Eijiro Hikari. Kamen Rider Kiva-la rescues him and both escape the ship's destruction unharmed. However, the Neo Organism has also escaped destruction and assimilates the Dummy Dopant to become Ultimate D. Decade and Double fight Ultimate D, having trouble until Decade produces the Kamen Rider W Final Form Ride Card. He uses it and splits Kamen Rider Double CycloneJoker into Double CycloneCyclone (controlled by Philip) and Double JokerJoker (controlled by Shotaro). Together, the three Kamen Riders perform the Triple Extreme Rider Kick and destroy Ultimate D. Soon after, as the other Riders take their leave, Tsukasa and Shotaro part ways after Tsukasa hands Shotaro a Kamen Ride card with Skull's image on it. Shotaro is then approached by a Sokichi Narumi from an A.R. World, who tells him the way Shotaro wears his hat is proof of him being a respectable man as well as saying they should meet again. Tsukasa returns to the Hikari Studio where a new backdrop depicting an endless road falls as the others wish continue to journey with him. Tsukasa, Natsumi, Yusuke, and Daiki all pose in front of the backdrop as Eijiro takes a photo. In Futo, as Asami accepts her sister's death and move on, the party resumes at the Narumi Detective Agency, with Shotaro reassured of his task to follow through with his mentor's wishes.