The undead of China: the souls of persons who have not earned sufficient merit during their lives on earth to warrant promotion to the afterworld, and must continue a miserable existence on earth. This fate makes them angry and evil, always on the lookout for sinners on whom to take their revenge.
They resemble skeletons except that their skulls are fronted with demonic faces. K'uei always move in straight lines, and so they are easily furstrated by setting a screen just inside the doorway of a room. They cannot move around the corner of the screen and so must go elsewhere in search of prey.
It is also advisable to build roofs with upward-curving gables, so that K'uei cannot slide down them and pounce on anyone standing below.