Takimoto, an ordinary salaryman, finishes a late-night overtime shift when he unexpectedly gets morning wood, caught in the act by cleaning staff member Tadai Mahiro. Though Tadai usually blends into the background at work, Takimoto can't resist the sight of her alluring figure faintly visible beneath her uniform, and impulsively tackles her on the spot. Despite her plain appearance, Mahiro turns out to be insatiably horny, quickly letting Takimoto creampie her. To his surprise, she's gifted with an incredible pussy, and they seize every spare moment during her work hours to fuck relentlessly. Their secret affair gradually deepens within the confined space of the workplace.