A pocket dimension specifically for hiding your horns? Damn, demons really take crazy magic for granted, huh?
(I say, typing my words into a rock filled with lightning that broadcasts them into a worldwide network of similar devices for the sole benefit of anyone else obsessed enough with this manga to read the comments on a bonus chapter.)
Interesting to know about the hood, that means a lack of horns/ears on Ameri's mom in the one panel we see of her doesn't actually prove anything since hats could have the same effect.