Drifting Tokyo Cosmology Sketch
Basic stuff familiar to cosmology 1. The umbra will look different when viewed from other places.
Earth, the mortal coil, Ashihara no Nakatsukuni, IRL. Occupied by humans, and similar creatures.
The 'penumbra' or 'mirror world'. The spiritual shadow or aspect of the human world, occupied by its various kami and other subtle creatures. In modern times the spirit world is separated from the human world by the barrier called the Gauntlet or Kekkai, strongest in cities, weakest in the deep countryside or places of spiritual power.
Supernatural realms connected to the human world, inhabited by creatures categorised into various forms of majin, mazoku, youkai and so on. While often termed 'demons' by Western mages, they do not govern the afterlife and are not concerned with damnation in the religious sense. Nonetheless they often covet the wealth and power - in goods, quint or creatures - that can be found in the human world.
(many places normally rendered as 'hells' can be found here)
Yomi no Kuni
The low umbra. The Yellow Springs. The world of the dead. A dark and polluted land where shades wander. Ruled by Izanami, and prowled by shinigami.
Regions of torment beneath Yomi for particularly awful souls. Presided over by the Yama Kings, who have duties to fulfil but have become increasingly corrupt in the modern age.
Yume no Kuni
The realm of dreams, where humans go to escape their iron cage. Many creatures who have made the same decision await them there. A mysterious and unmappable place, even for spirits.
Blessed lands far above the turmoil of men and demons. Sometimes glimpsed, rarely visited, at least by those who return to speak of them.
The realm of the heavenly gods. Accessible, in theory, by the floating bridge of heaven, but this has not been possible recently if it ever truly was.
The deep umbra. The void beyond the Great Barrier (Dai-Kekkai). There are many theories of the nature of this place, whether it is the chaos that preceded existence, or a space separating our world from others, or a last obstacle to enlightenment that can only be transcended by renouncing the desires it so eagerly responds to.
The moon is an unusual realm embedded in the Dai-Kekkai. The near side has a dual-aspect like the human world, between the barren desert of the Apollo missions and the silvery realm of the various lunar creatures. The far side, exposed to void, is a perilous and mostly empty place.