Nojima Yoshiki

A teacher at the school. Previously it was co-ed, but with the decline in male enrollment, he was forced by Aion to take on the role of caretaker of the dormitory, which now only has female residents.
Since then, he has endured daily attacks from the residents, who dislike the protagonist, the only male living in the all-female dormitory, but one day he discovered a training room hidden in the dormitory, and realized his sadistic tendencies and his desire for revenge against the dormitory residents, and he became obsessed with fantasies of abusing them.

When he was found by Satori while doing so, he felt the need to silence her, and he let out the desires that had been building up inside him, making his fantasies a reality by abusing Satori.

After that, he let go and saw the girls who had been trying to drive him out as prey, and decided to abuse them.

He originally became a teacher because he had a caring nature, and was a normal adult man with good sense and reason, but he was worn down by the daily attacks from the students, and became a completely different person after his encounter with the training room.