Info:
Blue Exorcist (青の祓魔師（エクソシスト） Ao no Ekusoshisuto) is a manga written and illustrated by Kazue Katō. It was adapted into an anime television series of 25 episodes by A-1 Pictures during 2011 and it will be adapted into an anime film. An OVA has also been released in 2011, called "Ao No Exorcist: Kuro no Iede(クロの家出)".

Story:
The story revolves around Rin Okumura, a teenager who discovers he is the son of the god demon Satan born from a human woman and is the inheritor of Satan's powers. When Rin's guardian dies while fighting Satan, Rin decides to become an exorcist in order to defeat his father. Entering into the True Cross Academy to learn how to fight demons, Rin meets several other exorcist apprentices who he starts to bond as well as his his twin brother Yukio.

Source:Wikipedia