Rin married Sentaro and became a stepmother to Sentaro's son from his previous marriage at a young age, Manji. Manji grew up being constantly told to study by his father from an early age, so he had no knowledge of sex, and didn't even know how to masturbate. Because of this, Manji would have wet dreams and soil his underwear almost every day, so Rin felt responsible as a mother and taught him about the female body and sex, saying, "From now on, I'm going to teach you how to masturbate. Don't tell your father, and don't touch me either."