Mami and I had known each other for a while, but I rarely kissed her, and sex was even rarer. Today, Mami's parents are traveling, so my girlfriend invited me to play at home and can spend the night there. Great! The first time I spent the night at my lover's house, just thinking about the two of us sleeping in the same bed, and then comfortably "abc xyz" was already very exciting. But suddenly Mami said that she had an older sister, Yume, and I was a little surprised because I always thought she was an only child. When I arrived at Mami's house, Yume immediately came to talk to me. Ms. Yume is an extremely happy, sociable person who likes to ask "sensitive" questions. I didn't pay much attention until she exposed her ass in front of me even when Mami was next to me! I was quite confused, but I couldn't take my eyes off her so perfect body. And when I was talking to Mami in the room, Sister Yume immediately found an excuse to get my girlfriend to go out, and she kept using her body to seduce me. Unable to resist her beauty, I immediately put on a condom and officially fucked my girlfriend's sister in her room! But while fucking, Yume stopped and took off the condom. I knew this was dangerous, but the pleasure of fucking naked made me unable to think about anything. I fucked her like crazy and drained all the sperm into her pussy over and over again! And for two days and a night at my girlfriend's house, I "ejaculated" countless times inside her uterus while my girlfriend was right next to me...