Arriving in Kaito's homeworld, the World of Diend, Tsukasa finds the world in peace and harmony, but with Kaito a wanted man. As Tsukasa assumes the role of a traveling salesman, he meets Kamen Riders Larc & Lance as they battle a Darkroach. After destroying the monster, Tsukasa learns that the world's residents kill Kamen Riders. As Tsukasa and company meet the head of area management committee, Junichi Kaito, Larc and Lance battle the Darkroaches until they receive aid from Diend. Saving them from reinforcements, Tsukasa learns from Haruka and Shin that the world is ruled by the mysterious Fourteen who uses his Roaches to manipulate humans.

Nearly killed by Lance, Kaito is spared when Larc stops her partner as he reminds her that he is the reason that Junichi is under Fourteen's control. After escaping the angry mob, parting from Haruka and Shin, Kaito and Tsukasa find Natsumi who tells them that Yusuke has been kidnapped by the Roaches before Junichi arrives. After remembering the events leading to his brother's enslavement, Kaito is reluctant to fight as he and Tsukasa transform to follow Junichi, leaving the brain-washed Yusuke behind and taking Natsumi to undergo the process as well.