My sister wanted to take a bath with me for the first time in a while, so I thought, "Oh well," but when I did, I was surprised to see that her breasts had swelled a little! What's more, the modest swell was just the size I liked, so of course it was a big hit! As I was washing my sister's body, I realized that her face and body were just my type, and I got super erect! I couldn't hide it and she found out, and I thought it was over... but in fact my sister, who was horny, started asking for me, and it was a divine development! I couldn't hold it in any longer and it developed into a forbidden incest!