I can't believe I get an erection from my older sister's naked body (big breasts)! My sister took a bath with me for the first time in a while on a family trip, and my breasts were bigger than I expected, so my crotch was so hard that I couldn't maintain my rationality... 4

It's been a long time since I went on a family trip, and I went to a bath with my sister! ! My sister's naked body (big breasts) I saw for the first time in a long time was so stimulating for me that I instantly got an erection! However, I tried so hard to hide this that my sister wouldn't be able to find out...but my sister quickly found out... Just as I was prepared to insult my sister, my sister's hand came across my crotch! why? My sister was in a slight panic and throbbing me!