The Secret of Dr. Hong

Doctor Hong Gye-Dong has mysterious eyes that can see people's threads of life. Actually, Hong Gye-Dong is a woman. One day, due to unavoidable circumstances, she ends up getting caught while shifting a drink bill to a man she thought was a scholar. Entangled with a dangerous man whose thread of life she can't even see, Hong Gye-Dong enters the medical clinic of the royal family.

But as it turns out, the man Hong Gye-Dong thought was a common scholar is actually the King.

(Source: Naver Webtoon, translated)