Blue Exorcist

Rin Okumura is a teenager with a natural gift to get himself in trouble. Despite that he tries his best to meet the expectations of his twin brother Yukio and Priest Shiro Fujimoto, who acts as their guardian, until he finally learns about the dark secret behind his origin.

Fujimoto and his companions try their best to protect Rin from the demons who are after him, but he ends up posessed by Satan, the most powerful of the demons and Rin's father. Seeing his guardian taking his own life to protect him fron Satan, Rin decides to fight back by unlocking his demonic powers, even knowing that by doing it he would not be a human anymore.

As part of his training to become an Exorcist, Rin gets himself enrolled at the True Cross Academy. On his first day of classes, Rin becomes shocked to know that his twin brother Yukio is already an Exorcist and will be one of his teachers.

Yukio sets out to the school's Exorcist-only shop to stock on some supplies along with Rin. There they find that the owner's daughter, Shiemi Moriyama, is being afflicted by a demon that dwells in her family's garden and, to save her life, they confront it by themselves.

Having Shiemi as a new classmate, Rin's total disregard for classes brings forth the anger of another classmate of his, Ryuji Suguro, aka "Bon". After learning of Bon's story, Rin finds that they have more in common than he would like to admit.

Rin and Yukio find that the responsible for their meals at the dormitory was Ukoback, a cooking familiar appointed by Mephisto Pheles to aid them. They also learn how Ukoback can be troublesome when he gets angry.

Eager to make new friendships, Shiemi asks her classmate Izumo Kamiki to be her friend and she pretends to agree, but Rin soon realizes Izumo is just taking advantage of Shiemi's kindness instead. Later, the students are reunited at the old dormitory to take part in the Exwire exam, where a demon attacks Izumo and her friend Paku by surprise and it's up to Rin and Shiemi to protect them.

Still troubled after her friend Paku decides to leave the Exorcist lessons, Kamiki gets involved in a fight with Bon and the entire class end up punished by Yukio. Just after Yukio leaves for a mission, the students are attacked by another ghoul and while trying to help the others, Rin learns that the monster was sent by one of his teachers who wanted to confirm that he is the son of Satan.