I went to a hot spring with my sister on a family trip for the first time in a while, and I was surprised to see that her breasts were bigger than I had imagined! My eyes were always drawn to her chest. I wanted to rub my sister's big, soft-looking breasts...and they were so hard they hurt! I never thought I would get an erection from my sister! Of course, I was so upset that she found out right away and started teasing me, looking awkward. But before I knew it, my sister's eyes had changed into those of a lewd woman looking at a man...and we ended up committing incest, which should never be done!