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.

Rin bears witness to the fateful Blue Night when his mother, Yuri Egin, gave birth to both Rin and Yukio. Rin never wanted to see-or even know about-his birth, but now he has learned something about himself that he may need in the coming conflict. Meanwhile, aboard the airship Dominus Liminus, the Illuminati and Lucifer move forward with their plans to bring forth Satan and return the world to nothingness.

Lucifer has welcomed Yukio as an ally, but Yukio has other ideas...