My girlfriend's sister suddenly came to stay over at my house, where we live together in a room less than 5 tatami mats in size. We had no choice but to sleep side by side, and in an unexpected turn of events, my sister started touching my dick and asking for it. Even though my girlfriend was sleeping next to me, I couldn't hold back at the sight of my sister trying to suppress her pleasure. I was more excited than usual, and in the end I couldn't hold back and ejaculated in large quantities!