Aki Rosenthal's ARK avatar. A big muscular man with a beard, mustache and very often with an otter around his neck. His clothing is usually just a pair of shorts, but sometimes wears glasses and/or a Hawaiian shirt.
MukiRose (as a word) is also associated with Aki's feats of strength/fitness, gutsy moves, and other overly macho things.
On November 11th, she did a mock debut of him as a Vtuber, much akin to Coco did with Coco Kaine