My girlfriend has a twin sister who is plain and serious and has nothing to do with sex! I mistook this serious sister for my girlfriend (older sister) and immediately fucked her raw from behind! I made her cum over and over again with my raw dick without realizing it, but then I realized it was my sister and not my girlfriend and apologized desperately! I thought it was Ito, but the plain twin sister was in heat and shook her hips and cummed over and over again! She suddenly turned into a sluttier woman than her older sister, and let me have raw sex with her, which my girlfriend (older sister) would never let me do!