And I hope the first comment was written trollifically. Hitler?!? Plus, you're registered for a manga site and this is the manga you're offended at, to the point of calling it "a crime against humanity" that it exists as fiction? Don't go read about Pokemon, they're kept in little balls!
This is my opinion, the kind that you might get back when you put an opinion out there, especially one that no amount of rereading carefully could make sensible. Because I try to not be a hypocrite, I'm ready to have another opinion thrown back at me, too. [shrug]
This is a lovely, creative what-if fantasy that should not be offensive to, say, ~90% of manga readers out there. The 10% who would be expected to be offended would be Christians (like me) who consider (unlike me—REPRESENT!) writing a demon king named Satan into a story where he's written sympathetically ranges from icky to dangerous. ... Meh. Paper tiger at best. Cuz, it's paper.
There is a plot underneath everything which was so well laid out in retrospect, but which I had no idea about until I reached it. That's why I had to come give the manga a 10. I've kept the last few chapters unread, though, because I'm going to miss it more when I'm done than I thought possible when I started.