The black and white tuxedo cat frequently drawn by Matataku. It's actually the artist's real cat (named after the moni-moni sound effect for cats kneading). His wife found it as a stray kitten on November 5, 2005 (Danbooru post #1340999), and they kept the cat until it passed away on October 26, 2022 (Danbooru post #5805672).
Easily recognized by the black stripe directly above its nose and the black spot below its nose on his right. Also was the best cat ever.
