Furin mikkai: Fushidara kurui shiri [不倫密会　ふしだら狂い尻]

Chiaki married her husband Onishi after an affair. Even after several years, the couple's relationship remains happy. Her best friend Nami married Haruki, a friend from her university days, and became a full-time housewife like Chiaki. One day, Onishi's company went bankrupt, and Onishi himself was bedridden. He was banned from having sex, and Chiaki was left with an uncontrollable body throbbing. Then, Chiaki met Haruki again and ended up having a relationship with him...