Since their father's arrest Kohei Nishijima and his little sister Kanon were social outcasts.
He was mercilessly bullied at school, while she was raped by a group of thugs.
Kohei wanted to commit suicide, but Kanon proposed they take revenge before ending it all.

So, Kohei struck back at the cruel teachers students and teachers with equal cruelty.
From a virgin deflowering show for one girl's boyfriend to an orgy involving students and even the police, drugs and sex and rape were Kohei's modes of retribution.

[From DLsite English]