Nana loses her girlfriend Kaeun and meets her again a few years later in her flower shop, finding her married to a man. Still having feelings for her, she keeps in contacts but something terrible happens to Kaeun leading her to her death. Nana becomes heartbroken and depressed. One day, she suddenly gets a chance to go back into the past and saves Kaeun from her death.

Kaeun was sent back to Seoul from Paris to continue her studying there so she wouldn't have to keep transferring schools whenever her parents have to go to another country for their business. So her parents sent her to one of their old friends, the Park family. The Park family had one daughter, Nana, who is just a year older than Kaeun. She was those popular girls where everyone would fall for while Kaeun is the opposite of her, a quiet person who prefers to be alone. The two had met a coup