I would however be devastated that the best girl would them be related to Ameri with how things are going. Unless it's the bait and switch of this human having a lover in the human world.
It would make sense if Iruma has demon blood in him, but then if Ameri is potentially half human, yet was able to do a regular contract with a familiar, while Iruma summoned a demon.
I am still on the track that Delkira was maybe originally human? But was warped by the demon world similar to Iruma? Not sure
My theory is that they are people from the same clan (cause the have the same color of blue for their hair) as Iruma not his actual parents.
I always wondered if Iruma was truly the child of those humans? Because they don't look alike. Was he like switched at birth or did they adopt him. And is that the reason why they are so indifferent to him, cause he isn't truly their child? ╮(￣▽￣)╭ Maybe he is kind of a relative of delkira, cause how could he transform himself those wings or more like demon features...