Ikareta Kyoushitsu ~Konna no ga Atarimae no Jugyou Fuukei?!~

Haruka moves to a new room in her boarding school because of a leaky roof. The new room hasn't been used for years and is dusty. While her friends Yuki and Mariko help her move, they find an old, dirty notebook that have belonged to a male student who had lived there before when the school was still all-boys. The notebook is filled with explicit fantasies that strangely match the characteristics of the three girls. They decide to burn the notebook, but the next day, Haruka finds a piece of it on her desk. It contains disturbing content about a twin-tailed girl being violated during class with the teacher's permission. Feeling uneasy, Haruka throws the paper in the trash and goes to class. She doesn't notice the boys around her getting agitated since she is lost in thought about the notebook. After the second class, the teacher casually suggests they all violate Haruka, and the male students attack her.