Blue Exorcist Vol 22

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 seals binding the artificial Gehenna Gate are broken, and the world is gripped by demonic chaos! As the Exwires try to figure out what to do without Rin and Yukio, and the Knights of the True Cross scramble to regroup, everyone seems lost. As nations around the world struggle to contain the outbreaks, Rin faces Mephisto, demanding to hear about his past. Mephisto couldn't be more delighted to show Rin what happened all those years ago - but as Mephisto warns him, the story can only end in tragedy.