As summer draws to an end, the homeroom teacher gives Yumi, who is having a hard time deciding on her future, guidance after school. However, the typhoon is stronger than expected and moves faster. Then the trains stop due to a power outage. Unable to return home, Shion and the teacher decide to spend the night at school... Until now, Shion's body was thought of as that of a girl... Her plump body is revealed through her wet uniform. "Teacher, this is our little secret." The teacher, with an explosive sexual desire, goes wild in the raging storm!