One day, when I went to wake up my sleeping sister, I accidentally caught a glimpse of her panties peeking out from under her cute pajama pants. Looking closer, I couldn't believe it—she was wearing a thong! Doubting my eyes, I slowly pulled down her pajama pants to confirm, and sure enough, it was a genuine thong. My heart started racing at the sight, completely captivated by my sister's ass, and I instantly got a full erection. Taking advantage of her being asleep, I couldn't resist the urge to play a prank, but soon lost control and penetrated her from behind while she lay face down. Surprisingly, instead of resisting, she seemed to be thoroughly enjoying it. *Note: This title features one performer selected from the previously released work "HUNTA-923." Since the content overlaps with the previously released multi-performer version, please be aware if you've already purchased it.