He's My First Man, A Devil

A mysterious, silent, alone, commoner man suddenly turned into demon. His appearance changes into a real demon but his heart never change even one beat. He was inlove to a woman who once became his bestfriend and childhood sweetheart but they separated because of an unexpected incident. The woman lived alone with forgotten memories with him and later on she fell inlove with the another man.

After many years they meet but forcedly.