Jung Seok is a librarian who goes about his daily life with everything planned down to the second. Having obsessive-compulsive personality disorder, he wakes up, crosses the road, visits the convenience store and goes to bed at the same time every day. Whenever he sees anything out of place, he can't help himself but rectify it, a trait that is particularly irksome to his co-workers. Jung Seok develops a crush for a local convenience store's cashier who demonstrates a similar attention to order and cleanliness. When he finally works up the courage to tell her his feelings, he bumps into So Jung instead, a messy musician and free spirit whose life is lived spontaneously, adventurously and impulsively. With So Jung's help, he tries to woo his dream girl, but the only catch is that she wants someone who doesn't share her obsession for neatness. So now Jung Seok must break his routine and place himself outside of his comfort zone, as So Jung asks him to enter a singing audition program together with her.