As a reader I am liking this series...but the tone so far is really weird to accept from a meta standpoint. Like, we establish that individual demons like the tutor and mom are quite nice and reasonable people, and that the demon kingdom was formed with best intentions...
And yet we know the converse of the human side where they're brutal expansionist invaders who wantonly murder and rape, all in the name of their evil god (who is named "Cannibal" of all things). On top of that, we know at least their royal society is pretty petty (i.e. only the strong call the shots).
I get that the author wants to set up a complex morality conflict with this story, but so far it's still fairly hard to stomach. I can't imagine being satisfied with the MC siding with secretly sabotaging the demons OR trying to reconcile with the human lands if it proves the demons have their own right to exist beyond their dark pact with Cannibal.