Read manga: Rule - Annihilation Classroom -

manga
Summary:

Yashima Kashiwagi is a freshman who has transferred to the elite Kusushu Gakuen High School. He quickly became friends with Hasebe Yuki living next door and Kimi Miyazaki. He tries to adapt to his new environment and being friendly with everyone but apparently the class has some "rules" that everyone must obey otherwise there will be consequences! What does this mean though? A reason for bullying or something more sinister is happening?