"You're an angel, I can never be with you..."  

"I'm here for you though, I'm here to help you.." 

"It's impossible, Damn it. We can never be... Just understand that!"

Imagine being a demon, a crude and morbid demon...

A demon that wants to be a part of the light,

but can never change.

A dark side to you, that feels so painful,

yet so good at the same time. 

What about an angel.. wanting to help.. wanting to change them to light.. 

but no power to do so.

Yesung , the evil demon of Hell, is nothing but a cold-blooded entity. He kills humans for fun, tortures, and lives off of their souls' energy. The more energy he gets, the closer he gets to becoming a full living being. Though doing so, he makes it seem like he's just doing the deed for Satan, but he is only trying to do what he wants. Wanting more  than just gore and evil. He wants something different.. like the light. The thing he can't have, he wants. An angel, a messenger of the Divine spirit, named Ryeowook, is sent to help this evil entity. To try to show it to the light.. only when everything goes downhill. How can the two be together without being hurt? They can't. They'll have to search through the darkness of love that brings them together, to unite and fulfill the Divine's wish.