My girlfriend has a little sister who is a high school girl. One day, when I went to her house to play, even though her older sister was nearby, her little sister pressed herself close to me and whispered dirty words in my ear while stroking my dick until I was on the verge of ejaculation. When my older sister was asleep or in the bath, I forced myself to have creampie sex with my little sister. I felt guilty, but my little sister was too devilish and I couldn't resist...