Japanese take on Will O The Wisps as ghostly possession. Will O' Wisps are what happens when swamp gas ignites, resulting in spectral blue flames floating in the air. Ancient cultures across the globe tended to associate this with the spirits of the dead and other supernatural forces. Sometimes, when a character is suddenly mortified or depressed about something, they will be portrayed as squatting in a (possibly nonexistent) corner, back turned to the main cast, with a black halo and ghost lights. Examples of Ghost Lights include: