Six years into marriage, a housewife works as a swimming instructor at a fitness gym. She had been working part-time at a gym since her school days and married a salaryman who used to attend the same gym. Her husband, eight years her senior, stopped going to the gym after marriage, and his appeal as a man gradually declined. Their marital relationship lost its spark, and the frequency of sex decreased. Lately, whenever she sees muscular men at work, she feels a rising desire, to the point of masturbating in the gym restroom. Unable to suppress her growing sexual urges any longer, she turned to adult videos to find release.