After drinking too much with coworkers at an izakaya near the office, office lady Kyoko finds herself unable to go home. Her junior colleague takes her in, but overwhelmed by alcohol and the temptation of her voluptuous body, he ends up raping her. They are discovered by the building's security guard, making the situation even more complicated. On Sunday morning, Kyoko is found shivering, naked under a blanket, when the guard approaches her with a lewd gaze. "If this gets out at the company, you'll be fired," he says, pressuring her to keep it secret. As a result, Kyoko ends up taking his thick cock into her mouth, marking the beginning of her physical training. Coming to work without underwear, bound tightly and left abandoned, she plunges deeper into pleasures she's never experienced before. Her body and mind gradually transform as she crosses new boundaries.