My sister's friend who often comes over to our house is a modest and cute girl who feels insecure about her big breasts. When she came to stay the night, I was lucky enough to find her wearing a swimsuit and take a bath with her, and I was surprised to see that she had huge breasts! Even though I knew it was wrong, I decided to sneak in and cum inside her! I couldn't help it and ended up cumming inside her, but instead of getting angry, she told me about her troubles and showed me her breasts herself, saying that I was excited by her big breasts...