My wife and I are living a happy life, she is eight months pregnant with my first child. Just thinking this happy life would last forever, Tsubasa's sister-in-law suddenly appeared. She is an extremely free person. She has been traveling for the past six years, so I have almost no memories of this sister-in-law. But this sister is so attractive! When she's at home, she doesn't wear a bra, even the pants she's wearing are see-through, revealing her mysterious "slit"! Because my wife was pregnant, I couldn't make love for a long time. The accumulated sexual desire made my cock quickly become erect in front of my wife's hot body. She also discovered and came close to me, touched me and started to fuck me even when my wife was nearby! And so for the next time we continuously fucked each other. She always let me release all the sperm inside her, then let me rest for three days to accumulate more sperm and release it all inside her again...