A world where mages were kept secret from everyone else... it was hard for Zeref to fathom. In his world, magic was a part of everyday life; even those who couldn't actually use it benefited from it. Why did they have to hide in Naoki's world? Persecution? Fear that humanity in their world simply wasn't ready for it?

And demons... the Etherious were demons, but they were his own creations. Naoki was summoning them from hell itself, by the sound of it. And half-demons? He remembered Raven, from before. He didn't know it was possible for half-demons to exist, and not just because all except one of them would rather revert to their book forms and be thrown into an erupting volcano than find out.

... oh. Parasites. That... wasn't quite like ethernano, was it?

Whatever the case, Zeref was now officially interested. He didn't interrupt, only continued to listen.