While his wife was away on a trip, he had a forbidden secret rendezvous with his sister-in-law, Riho... As their relationship cooled, he could no longer resist her temptations... "My sister is probably having an affair while she's away..." But even so, his reason was blown away to the point that he thought it was no good... Day, evening, night, and the next morning, he repeatedly had intense sex with Riho, who was far more erotic than his wife, and came inside her over and over again. It was the best moment, as they continued to desire each other. He wanted to stay connected forever. It felt so good that his head melted from the sense of guilt and euphoria...