Rin, along with his twin brother Yukio Okumura are raised by an eminent priest, Shiro Fujimoto, but one day Rin discovers that their biological father is actually Satan! As the border between “Assiah” (the human world) and “Gehenna” (demon’s world) is intruded upon by evils, Rin vows to become the ultimate exorcist to defeat his own father, Satan. To hone his raw skills, Rin enters True Cross Academy to train with other exorcist candidates.