When Uta was in the third grade, her brother committed suicide after being bullied at school. In his journal, he wrote that he wanted to get revenge on them by dying, hoping that his death would scare them. In the end, the school refused to admit that any bullying occurred and protected the bullies, who laughed the whole thing off and rendered his death meaningless.
Vowing to get revenge, Uta attends the same high school as her brother, where the ring leader of the group has become a teacher. At the entrance ceremony, she learns that her homeroom teacher is none other than Yuichi Sasao, the man himself.
