Delcayi

In this world, mystical creatures such as dragons and demons make contracts or bonds with mortals to give them power and strength that takes in a form of any weapon they desire. You start as an orphan (you can choose your gender) who's very poor and weak. One day, you somehow stumbled in to a black forest looking for food and came face to face with a giant, black snake named Delcayi, the Overdeath. A ruthless and most feared snake who rumored to be a god of chaos and destruction.