Working as a cleaning lady in a mixed-use building, married woman Shiki Koharu is cheerful and energetic, well-liked by everyone around her. One day, exhausted, she lies down on a sofa and happens to notice a young man's crotch naturally erect, bulging tightly against his pants. Unable to resist, she gives in and eagerly pleasures him orally. Another person witnesses the act, and from then on, she is ordered to serve as the building's sexual caretaker, performing intimate services for the men.