From The Heretic Knowledge Vault
A creature that is either a pet or assistant of a magic user.
In Errant Story, a number of somewhat unique magical creatures are used by the mages of Tsuiraku as familiars. These include micro-tentacle monsters, micro-unicorns (which can fly), flying cats, owls (not seen, but cited as an example of how much abuse a familiar can take), and undoubtedly other interesting critters that we've yet to hear about. Some can talk, while others just make vaguely obscene critter noises.
In contrast to many other mythical worlds, in the world of Errant Story, familiars don't have to hang around their mage to have familiarish powers, nor do the mages seem to miss them that much when they're not around. Meji's abduction by Ian separated her from her exquisitely sarcastic black cat Ellis, but it didn't affect Ellis' acrid wit or power to express it in the slightest; it just meant that he has to vent his bile on Jon instead, which seems to suit him just fine, although it doesn't make Jon particularly happy (what's new about that?).
It is alleged that Tsuiraku has banned unaccompanied familiars, on the grounds they could be used as "self-guided smart bombs or some paranoia like that." Self-guided smart-ass bombs, perhaps? They've also banned "humanoid" familiars, which causes a certain confusion when Nookie goes looking for the imprisoned Mejinilis and gets ... misinterpreted.