Shikeishuu, Mahou Gakkou nite Kyouben wo Furuu

Kanaki Taiga is the school nurse and teacher at Celevess Magic School. While taking good care of his students who adore him, he also likes to spend time on his hobby; torturing and killing. When the magical prodigy princess Karen Holks Ortesia and her bodyguard Fina transfer to his school, Kanaki picks Fina as his next victim. But pursuing his target while not having his identity as "the eraser" being revealed proves to be more difficult then he anticipated. (Source: Mangamo)