Ao no Exorcist: Yuki no Hate-hen

Rin Okumura a half Demon has a mysterious past and knows about his identity. He wanted to become an Exorcist in training he faced a lot of problems. Has made a lot of friends during his training and they have to perform some tasks daily. He got pity on the humans and wanted to protect them from the Evil enemies. Rin was unaware of his legacy and later knew about his father, Satan. He has to do like his father but he wants to help. This leads to a lot of fights, Sacrifices, and struggles to make his friendship bond strong.