One day, Izumi is introduced to her husband Mikio's subordinate, Hirai, who has been transferred to sales. Hirai, captivated by the beauty hidden beneath her plain attire, confesses his feelings to Izumi, knowing she is his boss's wife. Initially rejecting him, Izumi, in a sexless marriage, finds her body recalling womanhood under his overly forceful confession and accepts the pleasure. The delight of her innermost being being rubbed by his robust penis is unforgettable for Izumi, who can't help but repeatedly engage in secret trysts...