Tag for the creature that appears in Jiji (Aardvark)'s Twitter profile photo and therefore serves as their avatar of sorts; a blue cube-like ghost creature reminiscent of the ghosts in the Pac-Man (Game) franchise. Fan art, especially ones of Kantai Collection, has already turned this avatar into a character separate from the artist.
Whenever this creature appears in fan art or art by other known artists, never use "Artist Self-Insert"; it should be used for its appearances in Jiji's own art per that tag's description. "Borrowed Character" can suffice as an additional tag.