Humans live in the Wide World of Assiah, demons in Gehenna. Allies still have animals in Assiah despite of the, although the two dimensions are not intended to interfere with one another. The humans that can fight those demons are called exorcists. R IN Okumura can be a boy that bears the curse of being Satan's illegitimate son. His foster father sacrificed himself to save him. To prove himself as well as to avenge his foster dad's death Rin decides to adhere to the course of the exorcist.