Yes it is :) but the bird is only the basis of my system it can go way more further (it will but it is secret). Demons are made by the sins of humanity so there is always a need for people to exterminate them. There is some important rules too, first everyone has its own demon at their second year of training for becoming hunters (my story begin in a castle where they are trained but it isn't a school life). Most are given at the baby stade to the new graduates. Some people made friends with animals or other living things and from their soul created a demon from them as they needed it (only a few people are able to do this). Some of them had demons before as they grow with one by birth for some specific reason. or some more adventurous made a pact.
First rule, you must control yourself because demons are demons (some rare exceptions apply) they shall try to use you for their own deeds you may own one but it doesn't mean it will obey you.
Second, as they grow they must not become stronger than you because they might kill you then they will be free and earn a great power from your soul. (those demons are priority to hunt down because they are very dangerous)
Third rule, you can't change your demon unless you want to lose a part of your soul maybe even all of it then you should consider to keep it alive no matter what.
fourth rule, if you already own a demon you can't have another it requires you to link directly your soul.
Fifth rule, they can die if they do it might kill you but you can still survive if your soul is strong. In that case it still might be long to recover.
I talked about exceptions lets take the example of hisun's sparrow since he was an angel and have a pure soul it's demon shall become his friend and would never kill him or betray him because of their friendship. Some demons are really evil others can be kind in their own way and there's even good ones. Contractual demon's are rarely good ones most of them have bad plans or were forced to created a link with someone they often ends up to kill their owners.
Finally your demon might tell you what it sees from up above but you must be an exception to see from his eyes because some people would earn too powerful powers.
its a little summary to let you see how it goes i'm always open to ideas but I kept some secrets for now because it would kill the punch.