Even though my sister has become a high school student, she still wants to take a bath with me, which is a problem! Because I love her... I'm curious about her breasts, so of course I strongly refuse to take a bath... But she's so persistent that I can't refuse her and when we get into the small bath together, I can't take my eyes off her huge breasts, which are much bigger than I expected! On the contrary, because the bath is so small, my sister's breasts keep hitting my arm! Of course, I get a full erection because they keep hitting! If I get an erection, my sister will find out...