The popular web novelist Yeon Seok has one big secret. He has been living for 300 years in order to achieve his first love. He is searching for his first love, Ha Yeon, who suddenly appears in front of him as a 25-year-old man. Yeon Seok, who never thought his first love would be reborn as a man, pushes Ha Yeon away at first. However, because Ha Yeon is Yeon Seok's editor at Sin Bi books, Yeon Seok can’t escape Ha Yeon and they naturally grow closer over time.