Present me, past you

The protagonist, Yeoju, lives in a class society similar to the past, and a few years ago, our country began to experience renewed Japanese interference. The day after receiving an acceptance letter from a company, Yeoju travels back in time to meet her ancestor, Kang Daniel. But Kang Daniel has already been king for 54 years?! He looks like an ordinary 22-year-old. Upon seeing him, Yeoju concludes that he doesn't seem human! What is his true identity? And will she be able to save her country, t