A romance drama about a semi-human vampire named Seon Woo-hyeol, who failed to become a human by a day out of 100 years, and a woman Joo In-hae, who doesn't have a single human decency, starting to live together and finding true warmth.

Sun Woo-Hyeol (TaecYeon) is half human and half vampire. He badly wants to become a complete human, but he missed his chance because of one day out of 100 years. He has a reason why he wants to become a human. Sun Woo-Hyeol is an early adopter who must use something new and is a trend-setter. He happens to get involved with Joo In-Hae (Won Ji-An). She works as a contract nurse-teacher and she runs a guest house. Due to her poor financial background, she went through numerous part time jobs. She is known as a cold-hearted person by others. Circumstances leads Sun Woo-Hyeol and Joo In-Hae to share a house together. Their relationship develops romantically.—from KBS (Canon y mus)