Talk:Nurarihyon/@comment-29325824-20191125094740/@comment-10429980-20191125123509

Also while it is always "dark" in a dark mamono realm (outside of areas where they use the "light of the four great spirits" spell), it is noted that there is still a day/night cycle, just that it's actually brighter at night thanks to how the mamono mana in the air lights up and the red moon shines. On the other hand, I think there are implications that its always "night" in undead kingdoms.

And yes, dark mamono realms do exist in Zipangu, MGE volume 2 notes that some of the pseudo brothel towns become them and give the areas a special ambiance.