The Prince of the Joseon Dynasty, Kim Myungsoo, and Lee Sungyeol have been friends since they were young. The reason why they have been so close to each other is because of Sungyeol's father being the most known teacher at Seonggyungwan and Myungsoo's father the King. They grew together and their friendship grew. But when Sungyeol was a child, he became ill, and almost to the brink of death. Then a miracle happened and the next day he was a happy child, but the prince never genuinely smiled after that.

...And then their story continues on when Myungsoo gets ready to become the new king and get married.

...Sungyeol doesn't mind Myungsoo becoming the king, but he doesn't like the idea of him getting married.