Exorcism
In Catholic Christianity, exorcisms are performed in the name of Jesus Christ. A distinction is made between a formal exorcism, which can only be conducted by a priest during a baptism or with the permission of a bishop, and "prayers of deliverance" which can be said by anyone.
The Catholic rite for a formal exorcism, called a "Major Exorcism", is given in Section 11 of the Rituale Romanum. The Ritual lists guidelines for conducting an exorcism, and for determining when a formal exorcism is required. Priests are instructed to carefully determine that the nature of the affliction is not actually a psychological or physical illness before proceeding.
Blue Exorcist
Rin wishes to become an Exorcist like his guardian to become stronger and to defeat Satan. He enrolls at the prestigious , an exorcist cram school, which is actually the Japanese branch of the , an international organization dedicated to protect Assiah (human realm) from the Gehenna (demonic realm). Much to his surprise, Rin finds that Yukio is already a veteran Exorcist and is one of his teachers. Thus begins Rin's journey to become an Exorcist, accompanied by his brother and his fellow students who quickly become his close friends.