Sarina is a wife in an apartment complex who is worried about her night life with her husband who has little physical strength or sexual desire. - Kishikawa, a middle-aged man who has just moved next door, comes up with the idea to recommend to her a tonic made by the pharmaceutical company he works for. - A few days later, he visited Salina's house and peeked through the open window, and what caught his eye was her obscene behavior as she ran her hands over her sweaty skin and masturbated. - The two were never supposed to meet, but after witnessing this masturbation, they end up having an affair so intense that they end up sweating...