Blue Exorcist, Volume 28 (Blue Exorcist #131-135)

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.

When Shiemi confronts her old nemesis Amaimon, the demon king of earth doesn't understand just how powerful Shiemi has become. But for Shiemi to achieve her destiny, she also needs to realize her own strength! Back in Assiah, Satan and his minions square off against Mephisto and the Knights of the True Cross to determine the fate of the world. After receiving some enchanted power-ups, the Exwires prepare to enact their battle plan. Rin himself is part of the vanguard that aims to engage the enemy head-on. The time has come for Rin to fulfill his promise to defeat Satan, the King of Demons!