Saki (34) is a woman who teaches physical education at a certain prefectural high school and is in charge of the swimming club. She had wanted to be a teacher since she was a child. She was hired after graduating from a local university of education. She became a teacher, married a teacher, and gave birth. Although she had a fulfilling teaching career and built a happy family, she suddenly reflected on herself. "I want to do something that I can't tell anyone about, even if it's just once in my life." Also includes adulterous sex with five other people.