The Classroom at the Top of the Hill

Izanami Aiko was a 'special' kind of person. She had a hard life at home, she had a dark, sinister past, and to top it off she had low grades. Originally, she was in the A class at Kunugigaoka Junior high school, considered one of the smartest girls in her class actually, but for some reason her grades dropped and she was booted to the class of rejects, E-class. She thought it would be horrible, full of brain dead delinquents, but she was wrong. She relized she would be right as home when her class was given a special task.
Assassinate their teacher before graduation.