Kang Yeosang just heard the news that his best friend of 7 years and the love of his life got engaged to her boyfriend and he wants to do anything to stop the wedding. But when he meets his best friends sister-Y/N-or the first time after learning about her existence, Y/N is heavily under the impression that Yeosang hates her and makes sure her sister knows. His best friend just wants them to get along. What will happen after his best friend plans for them to hang out for two weeks?