The heavens are divided into three worlds (at least at the beginning of the
story...): Hell, Heaven, and the Realm of Magic. Amagi Sayuri's world is
one of a lot of moral ambiguity. Most of the characters, even the demons,
are good at heart, and even the evil ones are sympathetic in their own way.
Therefore, her images of Heaven and Hell are rather unconventional ones.
This isn't a manga that many devout Christians will enjoy, even without
taking the shounen ai themes into account.
Hell (and demons)
Heaven (and angels)
Realm of Magic