Chorong and Suho have known each other since they were children, but everything changed once Suho had to move away when they were in middle school. They made a promise to each other that if neither of them had anyone to call their own, that they would be the ones for each other. 10 years later Park Chorong is now known as the leader of a rising girlgroup called A Pink and Suho is now known as the leader of the booming boy group called Exo. Neither one knows of the other's presence until their paths cross. Many things have changed but what will happen to the promise?