Mephisto is the chairman of True Cross Academy. He was also an exorcist who work together with Rin.
Mephisto is the chairman of True Cross Academy and also appears to be an Exorcist. After he was called by Rin Okumura through a cellphone given by Shiro Fujimoto, he appeared before the boy and gave him three options: be killed by Mephisto, kill himself or to kill them all. But when Rin gave him a fourth option, being that he become an Exorcist, Mephisto became intrigued and agreed to his request. It is heavily implied that he is a son of Satan along with his brother, Amaimon.
Mephisto Pheles is created by Kazue Kato, whose name is a pun on the word Mephistopheles, which is the name for another infamous devil, similar to his father Satan.
Mephisto's full shot.
In his regular form, Mephisto wears a white outfit, complete with a large hat, a cape, purple gloves and an umbrella. He also has pointy demon ears and is always seen with a mischievous grin on his face. However, he has the ability to transform into a dog which is coincidentally white as well.
Mephisto is shrouded in mystery, seemingly knowing more than he leads on. Careful and maticulous, he's always ahead of the game which makes it difficult to determine whose side he's on (if any). His eccentric looks and personality mixed in with serious moments often enabled him to lighten even the heaviest of moods.
Major Story Arcs
Mephisto: You must be kidding me!
Mephisto is first seen at Fujimoto's funeral, on a mission to eliminate Rin. After approaching the boy and giving him two primary options: kill or be killed, Rin give him his own demand, become one of them. Surprised and amused, Mephisto asks what his reasons are for becoming an Exorcist to which Rin answered that his ultimate goal is to kill Satan and hence he needs to get stronger. Mephisto bursts into laughter at the idea, but nonetheless accepts the boy and gives him special permission to enter the True Cross Academy.
Mephisto in class with Rin.
Upon entering the school, Rin realizes that he's lost and can't find his way to the dormitory. Soon after, a dog appears and messages the boy to follow him outdoors where Mephisto transformed back to his original form. He then informs Rin that he will accept him into his academy on one condition: that he keep his identity as the son of Satan a secret. After Rin agreed, Mephisto gave him a key that would allow him to enter a building where classes are held for Exorcist students only. Mephisto then transforms back into a dog and accompanies Rin on his first day of school. After Rin watches his twin brother walk into the classroom as the teacher, he begins to bombard Yukio with angered questions while Mephisto merely watches the exchange with interest.
Powers & Abilities
Mephisto the dog.
Mephisto has the peculiar ability to transform himself into a small talking dog. The full extent of his powerful is currently unknown but it has been mentioned that he is an honorary knight, two ranks lower than Paladin.