Having Shiemi as a new classmate, Rin's total disregard for classes brings forth the anger of another classmate of his, Ryuji Suguro, aka "Bon". After learning of Bon's story, Rin finds that they have more in common than he would like to admit.

The Exwires are tasked to look for the ghost of a child that is haunting Mephisto Pheles' amusement park. Rin and Shiemi manage to find the ghost first, but Shiemi ends up chasing it by herself while Amaimon, a higher demon and another son of Satan, steals Rin's sword and forces Rin to fight with him. Mean while another exorcist comes to defend him, and it is reveal to be an old friend of Rin's brother.

Ernst takes over as the True Cross' newest leader and appoints Yukio as the new Paladin. Armed with special weapons that drain the blood of the demons killed with them, the exorcists take part in a widespread crusade to erase all demons from Assiah. Rin and his friends start questioning why the order decided to take such extreme measures, but Yukio is determined to accomplish his task as Ernst claims that it is all part of their plan to destroy Gehenna, and with the Demon world vanquished, both he and his brother would become completely human again. However, Ernst's real objective is revealed when he uses Rin as a human sacrifice to bring Satan to the Human World, using Yukio's body as a vessel.