Original: 마이데몬
A pitiless demon becomes powerless after getting entangled with an icy heiress, who may hold the key to his lost abilities — and his heart.
An accidental date with Jeong Gu-won leaves Do Do-Hee feeling flustered. She later becomes a victim of an attack — where a rescue requires a contract.
Gu-won inexplicably loses his power — and finds that Do-hee might be the key to regaining it. But his efforts to take back his abilities backfire.
After another attack, Do-hee asks Gu-won to be her guard — even after his admission as a demon. Do-hee finds the loss of someone close suspicious.
Do-hee proposes to Gu-won, but he refuses. She later recruits him to investigate Ju Cheon-suk's death, but he faces an unexpected power blockage.
After a dramatic rescue, Gu-won and Do-hee begin having complex feelings for each other. Do-hee later tries to find a man to marry — frustrating Gu-won.
After Gu-won saves Do-hee's life, she receives competing marriage proposals. She ends up choosing one, and finds an alarming face at her wedding.
Do-hee and Gu-won go through newlywed pains as they move in together. Ju Seok-hoon begins to suspect Gu-won's non-human identity.
After a sudden attack on Gu-won, Do-hee rushes to save his life — and as life around her becomes more dangerous, she makes a surprising career move.
As Do-hee and Gu-won's relationship finally blossoms, Gu-won begins to experience a strange change in his powers — all amidst a larger looming threat.
Upon discovering his fate, Gu-won tries to find another way to save himself. But just as he and Do-hee prepare their ritual, she becomes a target.
Gu-won finds his power restored after rescuing Do-hee from a sure death — but with side effects. With no time to waste, the two investigate the attack.
A dream of Gu-won's past life reveals his tragic connection to Do-hee. After the two hear of a death, their suspicions of the Noh family deepens.
As Gu-won and Do-hee enjoy their bliss, he notices her unresolved trauma. The two later join Noh Suk-min for dinner, unaware of his true intentions.
Gu-won comes to Do-hee's rescue after a frightening confrontation with Suk-min. But Suk-min's revelation about Cheon-suk leaves Do-hee harrowed.
Police fails to find Suk-min's body, opening up a concerning possibility. Do-hee attempts to bury her feelings after Gu-won disappears without a trace.
Do-hee finds herself catatonic after her loss. Desperate for Gu-won's return, she makes a Christmas wish for her love — which Noh Suk-nyeo hears.
