“I told you I would remember you.” “It’s good to see you again, crown prince.” There is a girl named Kyungmin with a special talent of time traveling in the Republic of Korea in 2020. One day, Kyungmin meets the 18 year old Prince Gwanghae, who came to the present from the Joseon era. Although it was only for a single day, the two of them leave each other with unforgettable memories. After returning to Joseon, Prince Gwanghae is unable to forget Kyungmin for a long time, and waits for her while dreaming of reuniting with her. And due to her father’s sudden death, Kyungmin carries out a life threatening time traveling journey. And there, she meets the 27 year old Gwanghae.