The story revolves around a young time traveler who helps the people of the Joseon era. Instead of preparing for a math exam, which she struggles with, high school student Tan-bi is transported through time. A random jump into a puddle takes her to the period of the Joseon dynasty, where King Lee Do is in power. The girl from another era appears at a critical moment - the country has been suffering from a drought for many years, and the residents beg the gods for mercy, while the girl from the 21st century happens to have enough knowledge to help.