Mina finds out that she's going to have a step-sister who is a famous model. Her whole life changes as her step-sister Tzuyu comes to her school. The two start off on bad terms but when the two hear that their parents are going to get married, tzuyu proposes a deal with Mina. 'If you marry me they won't be able to marry and when they leave one another and they find someone else we can end this marriage'