THE MORTAL REALM
The Mortal Realm is a single plane in reality, a flat disc with a world placed atop it. The edges of their world fade out into endless ocean that eventually reaches the Celestial Realm. The Mortal Realm has all the usual trappings of a world, it has seasons and different climates, elements, ecosystems. (Although its seasons tend towards the grey and rainy.) Human populations reside in small towns, smaller villages, or large trade cities. The wilderness is dangerous due to the pressure of the Spectral Realm and other untamed and tainted magic.

THE CELESTIAL REALM
The Celestial Realm is the home of a species of godlike animal spirits. They have great power to effect the Mortal Realm and helped to shape it into what it is today. They have largely left their magic arts and rituals with mankind to do what they will. They interfere little these days. Their realm encompasses the Mortal Realm like a shroud, providing it with life, light, and protecting it from the cold entropy of nothingness.

The Celestial Realm is controlled by the titular Five Beasts, but there are many lesser creatures who exist there with them.

THE SPECTRAL REALM
The Spectral Realm provides the functionality of the afterlife for all spirits in the system. It is a sphere that presses on the Mortal Realm, the barrier thin and distended. The bubble has not burst yet, but the Spectral Realm does vent many malicious ghosts into the Mortal Realm. At the center of the Spectral Realm is a swirling vortex of chaos where the weakest spirits are drawn in, torn apart, and remade into amalgamations of themselves. These confused and tortured spirits roam the Spectral Realm howling and enraged. Strong spirits and strong amalgams hunt one another, looking to tear their prey apart and add them to themselves. They grow stronger, they grow more grotesque and fractured.

Sometimes spirits find slits in the barrier between the Spectral and Mortal realms. Without a body to structure and contain them, they are mutated by their contact with the celestial magic that sustains the Mortal Realm. They mutate in a variety of ways, we won't bore you with the taxonomies, but one thing is similar between them all: life in the Mortal Realm is nothing more than a source of energy to them. They want to take it, whether through bathing in human blood, succoring on the prolonged insanity of a village, or simply eating humans. All spirits have ill intent, all are destructive, and if you allow them to feed their means of destruction will only magnify.

THE PARALLEL
A thin slice of nothing that separates the Mortal and Spectral realms. It is an empty and imperfect reflection of the Mortal Realm but ravaged and made blurry by heavy spectral winds.