Tsubasa Haneda was coming to Tokyo for a concert, but her hotel was fully booked, so she ended up staying at her sister's house. On her first night there, she accidentally witnessed her sister and brother-in-law having intense sex. Already suffering from a sexless marriage, her body ached with desire, driving her to masturbate. She became cautious about hiding her actions from her brother-in-law, but the next day, while her sister was out working, he took the opportunity to make advances on her. Though she tried to resist with reason, her body gave in, succumbing to the overwhelming pleasure of his insatiable stamina.