Kenji is left alone at home while his wife returns to her parents' house for childbirth, enduring each day in solitude. Concerned about his situation, his sister-in-law Mai Arisu pays him a visit. Greeting him with her adorable smile, Kenji happily welcomes her, overjoyed at seeing her again after so long. However, behind her gentle appearance, Mai harbors dissatisfaction with her own marriage. The real reason she came was to have Kenji relieve her pent-up desires. Unaware, Kenji relaxes in the bathtub when Mai quietly approaches him. The moment her true intentions become clear is drawing near.