My older sister, though plain and reserved, is an absolute beauty when she takes off her glasses. I couldn't resist getting close and penetrating her without a condom, making her experience her first time inside me. (Royd-305)

My stepsister is usually plain-looking and doesn't wear makeup. But I understand. She's a beauty! My sister, troubled by interpersonal relationships, gets advice from her brother. This leads to a dramatic improvement in her makeup skills, gradually building her self-confidence. Ultimately, she transforms into a stunning beauty who turns heads. But I, as her brother, can't remain silent. One night when our parents aren't home, I impulsively confess my feelings, but she refuses, citing our sibling relationship. "Even without penetration, just friction is enough..." So, they make a pact of just bare buttocks, but—. Unable to tolerate just bare buttocks, the two young people cross the line. They engage in incredibly pleasurable unprotected sex multiple times. What started as a purely physical relationship gradually blossoms into a deep connection, becoming lovers.