Rosario + Vampire

Tsukune Aono, an average teenager, is unable to get into any local high schools due to his poor grades. However, his parents are happy to have him enroll in a private school called Yokai Academy, which he discovers is a boarding school for monsters. The school teaches monsters how to coexist with humans, including disguising as them, but any real humans on campus are to be killed. Although he fears for his life, Tsukune befriends a beautiful vampire girl Moka Akashiya, who likes the taste of his blood. Fighting a school bully, he accidentally removes the rosario around Moka's neck, and discovers that she turns into a powerful vampire with a completely different personality.