Ruri's boyfriend, with whom she lives, is going on a business trip for a month, and so he and Ruri promise each other to abstain from sex for a month. Ruri's sexual desire is about to explode due to this long and difficult period of abstinence, but she manages to endure it. The day before her boyfriend is finally due to return, a junior colleague from his workplace comes to her house to pick up some documents... Ruri, who has become liberated by her abstinence, is careless and talks to the junior without a bra, and the excited gaze of the junior makes Ruri aroused as well, and she ends up having an affair with the junior...!