Haru works at a breakup agency that ends relationships on behalf of clients. One day, she mistakes a man for her client’s boyfriend and accidentally breaks up with the wrong person, Woohyun, the team leader of another department at her company. As a result, Woohyun ends up breaking up with his real girlfriend. Overwhelmed with guilt, Haru struggles to face him, but instead of anger, Woohyun surprises her with an unexpected proposal... “Let’s date for one year.”