I was in the bath alone in the middle of the night after work, indulging in masturbation when I felt someone looking at me from behind. The bathroom door opened and a girl was peeking in. She was my older cousin who was staying over. "Let's take a bath together," she said, getting naked and showing off her grown-up body. We pressed our bodies together and washed each other, and she seemed happy at my dick's overreaction. She rubbed my dick against her enlarged tits and ass, and I couldn't hold it in anymore. "I'll teach you about adult sex," she said, licking my whole body and burying my dick inside her pussy.