Kamen Rider x Kamen Rider W & Decade: Movie War 2010
is the name given to the commercial promotion for theatrical releases of the Kamen Rider Decade epilogue film, the Kamen Rider W prologue/flashback film, and a third film that serves as a crossover between the two and finale to Decade (all directed by Ryuta Tasaki). Unlike its subsequent Movie War films, this film is more focused on Decade than W. The films were released on December 12, 2009.
Plot
Accepting his fate as the destroyer of Worlds, Tsukasa Kadoya fights and traps Riders from across the multiverse in cards. He receives help from a girl named Yuriko Misaki before they encounter Natsumi Hikari and Yusuke Onodera, who intend to stop Kadoya through differing means. She attempts to make Kadoya remember who he was, but he rebuffs her and leaves with Misaki to fight Onodera. Natsumi becomes crestfallen until Kivala reminds her that only the former can stop Kadoya and the latter can give her the power to do so.