Ghosts

Ghosts are the spirits of those who have died particularly humorous or tragic deaths, who haunt the world of the living. Ghosts are fully sentient and indistinguishable from their living selves- new ghosts are extraordinarily personable. Older ghosts tend to be rather deranged, but every ghost ages differently.
To determine which deaths count as "funny" or "tragic", all deaths are reviewed by one of three groups: The Lunar Pantheon, the Ghost Bureaucracy, or the Cat Heavens .
Ghosts retain all of the skills and abilities they had in life, with a few notable bonuses: incorporeality and invisibility at will, limited telekinesis, and the ability to reform several days after destruction. Ghosts are effectively immortal, though their existence can be dull- it takes active effort to be corporeal, and many of a ghost's natural needs and wants are dulled.
There is only one way to defeat a ghost: by filing the appropriate paperwork at one of the two ghost harbors. One of these ghost harbors is on the moon so, practically speaking, there is only one. This ghost harbor is located on the back of the great Dragon Turtle Ruko , who travels the seas eternally. For most, this is an impossible task- but mortals have innovated their own practical solutions. Most rely on the world-spanning Exorcist's Guild  to fill out and deliver their paperwork. For this to work, the ghost's name is still needed- leading to those malevolent spectres that exist to guard their names jealously.