An affair with a student. Mio couldn't stop herself from getting immersed in a relationship that is inappropriate for a teacher. It would be fine if no one found out. Perhaps it was a mistake to continue the relationship without thinking too hard, but the hot-blooded student has recently escalated his desires and started asking for a relationship even within the school. Mio refuses, saying that it is absolutely not okay. However, when he forcibly caresses her, her natural perverted nature makes her give in to his desire... Before long, Mio herself becomes addicted to the thrill and sense of immorality of an affair within the school.