Nao and Yusuke have lived happily on a lower floor of their tower for three years. When wealthy upper-floor resident Watanabe invites her to a party, she secretly attends while her husband is working late. Drinking in an apartment far larger and more luxurious than her own, she lets down her guard and sleeps with him. Expensive rooms, gifts, and relentless sex gradually conquer both her body and mind. After initially hesitating, she submits to the wealthy men, begs them to creampie her on a risky day, and becomes completely obedient to their demands.