The Morose Mononokean

"Yokai dedication" is the work of sending Youkai who stay in the "this world" for some reason from the "hidden world" that they should have lived to to the "hidden world".
One day, Hanao Ashiya, a high school student was possessed by a youkai, happens to visit "Mononokean", which is a youkai-like man, relying on the contact information she sees. It was Seimei Abe, the sullen Lord, who was there. For that reason, Ashiya decided to work as a servant of a monster. The story of Abe and Ashiya's youkai duo and youkai begins.