Coming home from club practice, my sister was taking a shower to wash off the sweat, and I just happened to peek into the changing room at the perfect moment. When I opened the door, I was met with an even more erotic scene than I'd imagined. Surprisingly, she had massive breasts, and I completely forgot she was my sister—my excitement overwhelmed me to the point where nothing else mattered. With my body fully exposed and my cock hard, I startled my sister, but still, I got an erection and strangely suggested we bathe together. Despite her obvious hesitation, she started washing my dick, and I couldn't hold back—I thrust inside her bare. The story's highlights include her huge breasts wildly bouncing, my cute sister's reactions, her tight, pleasurable pussy, and moments like when I apologize and say, "Sorry, bro, I'm gonna cum inside you."