Alright so I guess the basic summary would be.

A demon with the ability to make contracts with the gods themselves, after working for his king for several years decides to hunt his original prey, the humans as the war between humans and demons has ended.

He goes to the human land aiming to create pure chaos using his abilities but has to stop as he encounters some strange humans. He pauses his journey is joined by a beast man and a little mage to figure what is going on.

(Alright dis is a newbies work and all so I just hope that this is good enough)