My wife went on a trip alone. As our relationship cooled, I could no longer resist the temptations of my wife's younger sister, Yuki... "My sister is probably having an affair while she's away..." I still thought it was no good, and my reason was blown away... Day, night, and morning, while my wife was away, I had intense sex with Yuki over and over again, cumming inside her over and over again... The immorality felt too good...