During a family trip, I was surprised to find that my sister's breasts were much bigger than I had imagined when we finally got to bathe in the hot springs together. Before I knew it, my gaze was always on her chest... When I thought about how I wanted to rub my sister's large, soft-looking breasts, my crotch became painfully hard! Of course, she immediately noticed, and although she initially treated me like a child and teased me, when she saw my fully erect penis in front of her, she became aroused and looked at me with lewd eyes! And then it developed into an incestuous relationship that we absolutely shouldn't have!
