Having a conflict with her husband, Ai got upset and left to stay at her younger sister's lover's house for a few days. Here, an ironic situation occurred when her sister accidentally lent her the exact same outfit. With her body full of sexual energy, as she opened the door, she was greeted by a seductive pose of her lover, unable to resist, her boyfriend quickly inserted his penis inside. It was only then that he realized it was her sister, not his lover, but he couldn't blame her as their outfits were too similar. However, the story did not stop there, he mistakenly continued once again when her sister had just finished showering, this time seemingly awakening the sexual instinct within her. That night, she actively sought him out and made him satisfy her once more, thus beginning their days of illicit affair.