Siu Sai, the quiet and low-key sister-in-law. At home, she wears glasses and has no face, but one morning, she comes to her with light makeup. Her brother is very concerned about her, and she begins to change a little. The brother can't help but confess that he has always been in love with her. The sister refuses, saying that they are brother and sister. But they end up rubbing each other's panties, promising to end the relationship with just one thigh. Although it ended, the passion of that time still burns between them ......