Blue Exorcist, Vol. 31 (manga)

Rin and his exorcist classmates are caught in a secret war against the forces of darkness. Raised by Father Fujimoto, a famous exorcist, Rin Okumura never knew his real father. One day a fateful argument with Father Fujimoto forces Rin to face a terrible truth—the blood of the demon lord Satan runs in Rin’s veins! Rin swears to defeat Satan, but doing that means entering the mysterious True Cross Academy and becoming an exorcist himself.

The Knights of the True Cross begin their attack on Satan’s fortress in a coordinated assault. The lord of demons summons the powerful Asmodeus, the King of Lust, who relishes the chance to take on Shura. Osceola squares off with Amon, who doesn’t think much of the exorcists’ efforts.

The battle provides an opportunity for Rin and Yukio to breach the gate, but getting through it is no easy task. With Shura and Osceola barely hanging on, desperate measures will be required…