You know...I just thought of something.
Its not unheard of or uncommon for asexuals to not have sexual attraction, yet still be curious about/enjoy fantasizing about romantic and sexual activities, which means they can very much appreciate erotic stories or art. So I get where PK is trying to go with Beleth's asexuality, I really do, here's where it starts bothering me...
There keeps being this implication that Beleth = Jupet, who was a child. Beleth's "curiosity" of things and hentai obsession resembles much more like a really curious horny school girl, which is why there is so much confusion. So basically, what I'm trying to get at, is I feel like PK was trying to make Beleth's interest in sexuality "childlike wonder" or some shit, and that is a really offensive and inaccurate portrayal of asexuality, not to mention really creepy.
But, I think someone started pointing all this out, and PK back pedaled like, "DON'T WORRY ABOUT THE BELETH-JUPET CONNECTION BELETH IS NOT A CHILD ITS ALL OK." Suuuuure.