On Campus: Forced to Take Part in the Knight War

After spending 17 ordinary years in this world, Xu Yi, a student at Mingde High School in Linghai City, sees everything at school change when a new transfer student arrives in early September of his sophomore year... Pursued by Mirror Monsters, Xu Yi is drawn into the Rider War and becomes a Kamen Rider. Now he must survive the battle...

Setting: Mirrors reflect a person's true nature. The world inside them is called the Mirror World, where Mirror Monsters dwell. They occasionally attack and prey on humans. Riders can use the abilities of specific Mirror Monsters after making a pact with them through a card deck.