Pretending to be unaware, she seduces young women in puberty by showing off her underwear, causing erections. (Asami Mashiro, FSDSS-709)

Asami is my parents' younger sister from their remarriage. She's a beautiful girl, but extremely selfish. Seeing my sister with her pert buttocks exposed and her underwear showing was discovered. From that day on, I was seduced by Asami, who was very interested in sex, and forced to do whatever I wanted.