Kamen Rider × Kamen Rider Gaim & Wizard: The Fateful Sengoku Movie Battle

A battle royale is being held exclusively for the Armored Riders in Zawame City. Kamen Riders Gaim, Baron, Ryugen, Kurokage, and Gridon decide to enter the competition. While fighting, a crack opens in the sky and the Pitcher Plant Monster pour out from it. The monster soon returns to the crack, with the Riders giving chase. Soon, they find themselves in a Warring States Period-esque world where the Kamen Riders are called Bujin and are fighting each other. (Kamen Rider Wiki)