He is a male brown dog with dark-coloured mouth and nose in the 2005 version, but has a lighter mouth and nose in the 1979 version. Muku also wears green-coloured collar that Gian has gifted it.
PersonalityHe is shown to be a shy and unintelligent dog. Muku tries to be as brave as Gian, who praises his strength and courage, but in many emergencies he just runs away and enrages Gian. Muku is very fond of Gian's sister, Jaiko. At first, Gian didn't want him around and tried to get rid of him, but after he saved Gian from being eaten by a lion that had at first tried to eat Nobita, Gian warmed up to him. Muku occasionally shows the bad habit of gathering things from the locality in his kennel, much to Gian's embarrassment and his mother's displeasure.
Occasionally, in other manga chapters, Muku is shown as an aggessive and aloof dog, stealing from others.
Despite beating up Muku, which Gian occasionally does, he still loves Muku as seen in some episodes. Gian is quite cruel to Muku, not treating him very well. In some chapters and episodes, he rarely ever feeds or walks him. This could be the reason why he is very timid and ditzy.
- Despite being a dog, Muku is afraid of cats.