One day, her younger brother's gentle sister, Yume, learns that her younger brother is being bullied at school. Invading the boys' school where his younger brother attends, dressed as a man himself with the desire to help his younger brother. He tries to stop bullying by grasping the weakness of the main criminal case, but on the contrary, the biggest weakness is known. It means that Yume is a woman. Immediately, the days of nightmarish circles begin, being preyed on by barbaric men.