Ao, a mother who lost her husband and raised her only son Takahiro on her own, was unable to earn enough money and had to offer her body to her boss, Onuki, at work to earn a living. However, the pervert Onuki is not satisfied with just holding his girlfriend Aoi and begins to take an interest in her butthole. In order for her to survive, Aoi continues to have her anus played with every day as she is told. Finally, her anal virginity is taken away from her, and she reaches climax without even realizing it. Seeing this, Onuki seeks even more excitement and comes up with a plan...