The first time I met my girlfriend's younger sister, she was a cute J-girl with big tits. I couldn't resist the unconscious temptation of her unprotected uniform panty shot and got an erection, and my uncontrollable sexual desire and sperm headed towards her panties and ejaculated inside them! I asked her to wear the sperm-covered panties and rub them together, but when I asked her to do panty rubs, my freshly ejaculated semen mixed with my sister's love juice and made it soggy! I couldn't hold it in and it seemed to feel good from the rub, so I pushed her panties aside and inserted my penis into her! I was so turned on by the sight of my younger sister climaxing while arching her back and shaking her big tits that I couldn't stop thrusting and came inside her many times.