The class's latest mission is to search for a "ghost" spotted in an amusement park. Paired up with Shiemi, Rin can't shake off the feeling that he's on a date. They find the ghost, who keeps taunting them and running off, until the mission becomes a game of tag. Separated from Shiemi, Rin is confronted by the King of Earth - Amaimon! When he loses the Koma Sword to Amaimon, Rin finds himself being consumed by the power of Satan...!
The first semester has ended, signaling the start of summer vacation for True Cross Academy students. But there's no rest in sight for Rin and the other ExWires: first they must take part in a 3-day drill to prepare them for actual combat, under the guise of a camping trip out in the forest.
Consumed by the power of the flames during his battle with Amaimon, Rin goes berserk! He regains control of himself once his power is exhausted...only to be captured then and there by the current Paladin, Angel!
Rin is undergoing training so that he can learn to master his demonic flames. Just then, a giant bird-like demon called Gufu swoops in on him! With Yukio's help, he drives it away, but all of the Cram School members are sent to investigate how the demon infiltrated the academy... Suguro and the others are still investigating when Konekomaru appears, begging for help, with Rin in pursuit. According to Rin, Konekomaru's been possessed by a demon, but no one else can see it. Suguro, mistakenly believing that Rin is attacking Konekomaru, turns on him with hostility!
Hordes of demons are spilling out of Gehenna Gate! And these intruders from the "Empty World" are now indiscriminately attacking the people of True Cross Academy Town! Meanwhile, on the roof of the school building, Rin has been rescued by Suguro and Shiemi and is starting to come to. What Rin sees when he awakens is...
Satan has transformed himself into a gigantic Gehenna Gate, and is attempting to absorb all of Assiah by expanding a rip in the dimension. Rin and Yukio, joined by Shura and Angel, attack the gate, but it's an uphill battle against Satan's overwhelming power.
Meanwhile, at the school, the exorcists are in a desperate situation, as a myriad of demons attack. Just then, Suguro proposes a strategy for a comeback! But will it work? Rousing themselves into action one last time, Rin and Yukio head toward the gate. To protect their beloved friends, and this world!