A fire demon
is a kind of magical creature that can be found in the land of Ingary
. They are usually found, if at all, as the familiar of a powerful magic-user.
Magic-users with familiar fire demons include the Wizard Howl (whose fire demon is Calcifer) and [the Witch of the Waste]?.
The details of where fire demons come from, and why they associate with wizards and witches, constitute a spoiler for ''Howl's Moving Castle''.