Rosario + Vampire Vol 4

Rosario+Vampire by Akihisa Ikeda. A Fantasy manga rated Older Teen, published in English by Viz Media.

Tsukune Aono's grades were so bad that the only school that would take him was Yokai Academy, a boarding school for monsters disguised as humans. He's the only human there, and if anyone finds out, he's dead, though his new friend Moka, a beautiful vampire, may be able to protect him.