College student Jaeyeon gets hit by a delivery bike. She dies and reincarnates with her memories from past life. As a nanny of a little princess, she somewhat gets used to her new life... Except that she suspects the five-year-old daughter of the tyrant emperor is also a reincarnated soul from modern time-just like her! A complete mismatch, the princess and the nanny must collaborate in order to survive in the new world under the tyrant's rule.