Blue Exorcist, Vol. 28 (manga)

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!