Shiori is forced to let her drunken boss accompany her home after work when there's no last train. She stays overnight at her husband's place, but her boss accidentally discovers her giving her husband a sexual service that night. Captivated by Shiori's innocent appearance, the boss lies at work the next day, claiming her husband caused financial damage to the company, and uses this to blackmail her into submission. Wanting to protect her husband's position, Shiori resolves to sacrifice herself. Exploiting her pure heart, the boss begins to sexually train and corrupt her, turning her into his obedient mistress.