"Demons". Just humans that can use magic. So human mages. But they want to call themselves demons for some reason, and believe there is some sort of species difference between them?
Maybe someone should tell them that they're actually all just human?
Then again, while it is always translated as "demons", doesn't the word they always use for these guys literally translate as "magic race"?
(And I see this team is doing the fragmented chapters thing again. How utterly pointless.)