Ji Hyun and Lu Han are childhood friends, they used to spend every day playing with each other and made a promise to never separate until one day, Ji Hyun’s parents decide to move from Seoul, South Korea.

Ten years later Ji Hyun moves back to Korea without knowing about Lu Han’s whereabouts or what he now looks like. All she remembers of him are those from her childhood memories.

She enrols at a school where she meets some friends, Oh Se Hun and Park Yoon Jung. One day, Se Hun introduces Ji Hyun to his best friend not knowing that he is Lu Han. Ji Hyun and Lu Han get along well, realising that they have a lot in common.

During the year, Lu Han and Ji Hyun develop feelings for each other still not knowing they are childhood friends. A shocking turn of events happen when Se Hun confesses to Ji Hyun and Yoon Jung tells her she likes Lu Han.

Will the friendship of these four survive? Who will end up happy in love? Who will get hurt?