One day, Yui, a wife living alone while her husband is away on a business trip, comes home to buy a new fluorescent light bulb for the kitchen. By chance, a man from the neighborhood, Hirai, helps her out... However, once the bulb is replaced, Hirai takes advantage of her husband's absence and comes to Yui for sex... Yui gives in to his persistent requests, but since then, Hirai, who knows her lifestyle, has been lying in wait for her...