Fill Me Up, Mr. Assistant!

During the day he’s a administrative university assistant but by night, Shin Dowoon works as a demon hunter.
Before him appears the promiscuous incubus in the form of a human student named Lee Hayoon. Hayoon offers a contract in return for letting Dowoon capture him. But because of the devils tie up play, Dowoon has no sympathy.
Will this rough play be enough to satisfy the demon?