Kozue, a school nurse, is a beautiful teacher who is popular among students. However, in private, she has been trained by her masochistic husband and has become a sadistic woman who attacks her husband's anus every night. One day, a male student at school who has become interested in anal sex comes to her for advice, and she gently teaches him how to do it, making him fall in love with her. She invites the student, who is completely obsessed with her, to her house for a naughty extracurricular lesson...