Unable to resist my perverted friend's request, I peeked into my sister's bath with him. Seeing my sister's breasts and fluffy pubic hair after 10 years, I couldn't help but get an erection! Together with my friend, who was also fully erect, we couldn't hold back and pinned my sister down, licking all over her body. Despite her refusal, saying, "Absolutely not because you're my brother," I thrust my brother-penis into her and came inside her. I absolutely can't tell our mother.