Saki-san (34) is a female teacher at a certain prefectural high school, teaching physical education and coaching the swimming club. She's been aspiring to be a teacher since she was young, graduating from a local teachers' college and getting hired. After becoming a teacher, she married a fellow educator and had children. She built a fulfilling teaching career and a happy family life, but one day, she found herself reflecting, "I want to do something I can't tell anyone about, just once in my life." This includes footage of her having extramarital sex with five other men.