After inheriting her late father-in-law's public bathhouse, Nao and her husband become overwhelmed with daily operations, leaving little time for their marriage. One day, a regular customer named Takahashi, who always visits just before closing, offers to help work at the bathhouse. As Nao spends more time with him, she gradually grows closer to Takahashi, especially as her time with her husband continues to diminish. Despite feeling guilty, she finds herself drawn into an intimate relationship with him. Recalling the pleasure of their sex, Nao moans uncontrollably each time he thrusts his cock into her in the large communal bath, her body overwhelmed by waves of ecstasy.