Rie Kirisaki is a teacher who maintains a romantic and sexual relationship with her student, Yuuji Toono, fully conscious of its improper and inadmissible nature. Despite explicit warnings from her friend Ayaka, she continues the affair. Their encounters occur in multiple locations across the school grounds, including the staffroom and classrooms. The situation grows increasingly complicated when Yuuji's sister, Mao, who holds her own romantic feelings for her brother, discovers the forbidden relationship. Finding the circumstances unbearable, Mao is ultimately compelled to take action. Rie Kirisaki's appearance includes glasses, a shirt, a skirt, tights, and pumps.