Mū's entire body was covered by intricately wrapped seaweed green bandages, with only his violet-colored eyes and nose being visible, giving him an overall mummy-like appearance. Along with this Mu wears a dark blue headband with no distinguishing markings and a pair of black pants. He also doesn't wear shoes as his feet are also bandaged heavily. Due to the effects of the Summoning: Impure World Reincarnation technique, he has black sclera and white irises after Kabuto Yakushi eradicates his personality.
Mū was an extremely calm and collected individual, showing no signs of perturbation to his sudden reincarnation. He's also unfailingly polite, taking his time to recount the previous events to the other Kage upon their forced summoning, and referring to the one whom he killed and in turn was killed by with an honourific title, apparently bearing no ill-will towards him. In the anime, Mū was angrier at the Second Mizukage, even grabbing him by the collar of his coat and threatened to kill him.
Despite the seeming civility displayed towards his fellow Kage, Mū has demonstrated that he first and foremost prioritises the prosperity of his own village regardless of the manner in which this affluence is achieved, even reminding his disciple to take full advantage of any post-war situation to assure the dominance of Iwagakure by quickly seizing control of the resultant spoils. Even seconds before his sealing he attempted to warn Ōnoki to take precaution. This devious and somewhat merciless trait appears to be just one of the many reasons as to why the Second Mizukage despises him to such an extent. This under-handed tactic would later be taught to his student, which would become the reason for Iwa's bad reputation among the Five Great Shinobi Nations. However, in the anime, just before his soul returned to the afterlife, Mū had a change of heart and acknowledged that Ōnoki must secure the future of the Allied Shinobi Forces.
Despite Mū's views on alliances, he still attempted to help the Allied Shinobi Forces any way he could, even while being controlled. Right as one of his halves was sealed he attempted to warn Ōnoki he had split, but his message failed to reach his successor.
Dust Release Kekkei Tota:
Ninjutsu Master: Mu was able to split himself into two duplicates to help escape a lethal blow, but at the cost of reducing his power by half. He was also physically strong enough to lift massive rocks off of his body, even with only half of his power. It was impossible to detect him by normal means.
Sensory Perception: Mu was a skilled sensor-type shinobi, having displayed the ability to sense chakra over a distance of several kilometers, as well as to discern the similarity between of chakra signatures belonging to close relatives such as Gaara and his father, and distinguish chakra from different populations. Furthermore, when these detection capabilities were employed in conjunction with his quick reflexes, he could avoid techniques that even other Kage found difficult to evade, even from his blind-side.
Keen Intellect: He appeared to be both extremely knowledgeable and analytical, being able to discern the exact method used to locate his position almost immediately after detection, seemingly without any prior information concerning the technique in question. He also apparently deciphered the mechanisms behind his rival's Steaming Danger Tyranny and passed on the information to his student, as was later speculated by the Second Mizukage himself.