Sensei wo Kesu Houteishiki

At a prestigious high school in Tokyo, the third grade D class consists of high scoring students. Their previous homeroom teacher went crazy in a short period of time and quit their job. The students in third grade D class pushes their homeroom teachers to the edge and watches their teachers collapse mentally. The students view it as a game they enjoy playing. Tsuneo Yoshizawa appears in third grade D class as their new homeroom teacher. Tsuneo Yoshizawa keeps a smile on his face, even though he is attacked verbally and physically by the students. He never loses his smile. The students' behavior gets worse towards Tsuneo Yoshizawa and they concoct a plan to kill their teacher. (Source: AsianWiki)