{ World }

Maelstrom is a world that consists of three planes: the Overworld, home of holy immortal spirits; the Mortal Realms where mortals like humans, beast-humans, and some immortals dwell; and the Underworld where demon spirits reside. Immortal spirits were once able to traverse between their home plane and the Mortal Realms, but a powerful seal was created at the end of the Catharsis that shut away the Mortal Realms, leaving abundant immortal spirits stranded within the Mortal Realms and making it impossible for sentient spirits to cross realms again.

Mortals cannot survive in any other planes. Because of this limit to their scope of the world, the names "Maelstrom" and "Mortal Realms" are often used interchangeably.

{ Magic }

Magic is commonly practiced by the inhabitants of the Mortal Realms. The practice of sorcery and summoning refers to a user controlling, manipulating, or influencing demon spirits, holy spirits, and rarely soul spirit, to use as a source of energy for their task. Elemental magic draws its power from the essence of the Mortal Realms: the elements water, fire, air, and earth. Only beast-humans are known to be capable of using it.

At the beginning of the story, the kingdoms of Maelstrom had recently prohibited all uses of Common Magic--an alternate name for for Demon Magic, magic that uses demon spirits as its power source. This is due to the suspected link the widespread use of demon magic, the occurrence of Carciphonas, and the sudden appearance of an assassin that is immune to magic.