Taming The Younger Sister-in-Law

One day, Min-sang who is not that handsome becomes a huge success because of a webtoon. Then he gets a pretty wife, Yu-ra, for himself. Min-sang is having a dream-like marriage with Yura. It has been a perfect day except for his sister-in-law Yu-mi, who hates her ugly self. Accidentally, he learned of his wife's dark past through his sister-in-law's diary, and this leads to a reversal of the relationship with her sister-in-law. Min-sang began to demand excessive demands from his sister-in-law, and Yu-mi began to accept them. Where will the end of the relationship between Min-sang, Yu-ra, and Yu-mi lead?