The Kamen Rider Club discovers that the Dai-Zangyack fleet is moving towards Earth, led by Captain Marvelous as their Great Emperor. With many revived Super Sentai villains under his command, Captain Marvelous plans to obtain the Great Power of the Kamen Riders which is said to be "Ultimate Treasure in the Universe". Meanwhile, Tsukasa Kadoya becomes the Great Leader of Dai-Shocker once again and recruits past enemies of the Kamen Riders to take down the Super Sentai teams.

Tsukasa travels to his home world of the World of Decade, where he discovers the origin of his powers and his true heritage as the leader of Dai-Shocker. The film features all ten of the lead Heisei Kamen Riders, as well as all of the Shōwa period Kamen Riders, leading to a total of 25 Riders.

Serving as the true ending to Kamen Rider Decade and revealing the origins of Kamen Rider W, this movie is split into three parts. In "Kamen Rider Decade: Final Chapter", Tsukasa Kadoya fully embraces his title as the Destroyer of Worlds. In "Kamen Rider W: Begins Night", Shotaro and Philip recount the night on when it all began. Elements of both parts converge in the movie's final part, "Movie War 2010" as our heroes fight the forces of Super Shocker.

Eiji and Ankh team up with Kotarou and Momotaros as they travel back in time to 1971 aboard the Den-Liner to stop three Mole Imagin. But Ankh’s desire to obtain Core Medals while in the past sets off a chain of events that alters the 40-year history of the Kamen Riders by allowing Shocker to take over the world. It’s up to OOO and New Den-O to restore the timeline!

Under the impression that they saved the World of Den-O, Tsukasa Kadoya (Kamen Rider Decade) and company begin their journey to the World of Kabuto when they are halted by Sieg who presents them a manuscript that detailed the legendary Oni Conquest with Momotaros' image on it. As this occurred, the Tarōs mysteriously vanish from the DenLiner as they are about to help Kotaro Nogami (Kamen Rider New Den‑O) out with the true threat to their world.

Tracking a mysterious man leaping through the night air of Tokyo, Ryotaro and the Imagins find themselves in November 2008, where the DenLiner is stolen by none other than Kaitou Daiki, Kamen Rider Diend! As Daiki tracks his past self, he faces off with Time Police officer Reiji Kurosaki, aka Kamen Rider G Den-O! Just what is the connection these two men share and who will prevail when the trigger is pulled?!

Kamen Rider Decade: All Riders vs. Dr. Shinigami was a short film spin-off of the 2009 film Kamen Rider Decade: All Riders vs. Dai-Shocker. It was released on 1st August as part of a 7-Eleven promotional campaign.