Mad Girl Revenge: Kuzu Doukyusei, Zen'in Koroshimasu

Hagiwara is a high school teacher who has problems with the troublemakers in his class. One day, Yui Katsuragi, an ordinary innocent-looking high school girl, transfers into his class. She transferred to this school for one purpose only: to take revenge for her younger brother, Toru Kamiya, who had committed suicide. She sees Hagiwara, the teacher, as being equally guilty for failing to save her brother, and he gets caught up in her scheme for revenge! A mad high school girl brings down the hammer on the scumbag bullies in this horrifying revenge thriller! (Source: Owl Comic, translated)