From The Heretic Knowledge Vault
Kureji Mesuinu's familiar, or so it seems; first seen here, in the Fun with Familiars omake, although there's a tantalizing hint that he may have appeared in an earlier FwF vignette. He seems to be a micro-unicorn, the first example of that much-maligned species to appear on stage (albeit only in the omake at that). Kureji and Rokku Sona have inexplicably different views of his capabilities.
Isn't his name CUUuuute?...