The story of a woman who has gone through several reincarnations over the course of 600 years and remembers all of her past lives and a man who has lived for over 600 years as a mythical creature that feeds off human blood and is cursed with immortality.

Shin Sol-i isn't shy about her unrequited crush on Cha Heon, her next-door neighbor. One day, she gets an idea to write him the perfect love letter.

The tangled fates of the heiress of a cosmetics company and a woman who had to achieve everything on her own.