Nu

Mu is a snow spirit who appears in a single episode of the anime continuity of Ranma 1/2. Appearing in the episode A Cold Day in Furinkan, Mu is the central antagonist of the episode, due to his actions.

History
Mu arrives in Nerima one winter, following his mistress, the Snow Girl, when they are separated. Due to this, Mu becomes very anxious - worse, when he spots Ryoga Hibiki rescuing the Snow Girl, he becomes enraged, thinking that Ryoga is attacking his mistress. As a result, he begins to innundate Nerima with an unnatural blizzard, forming an enormous castle of ice and snow where he waits for the cold to kill off the humans and free his beloved mistress.

This behavior brings Ranma Saotome, Akane Tendo, and Ryoga Hibiki to do battle with Mu. After a fierce fight, he is subdued, giving the Snow Girl a chance to quell his rage and bring him back under control by the use of her flute. Once she has apologized for Mu's behavior, the two return to their home in the icy mountains of Japan.

Nature
Mu is a snow spirit of some undetermined, elemental-like nature. Less intelligent than the yuki-onna with whom he travels, he serves the Snow Girl as a devoted companion and protector, seeking to guard her against all threats - including humans who might interfere with her. Exactly how much intelligence or personality he has is ambiguous, but the absolute center of his world is his beloved mistress; everything he does is motivated by his desire to keep her safe from any possible threats.

Mu takes the form of a mass of snow clumped together in the form of a rudimentary humanoid shape, dominated by a single distinguishable feature; a massive, bright red, crystaline eye. This mass usually looms to an enormous stature, well over the height of a man.

Abilities and Weaknesses
As a snow spirit, Mu has a wide array of elemental powers. He can generate blizzard weather conditions over a wide area, dropping the temperature across Nerima in the span of hours to the point that fears of freezing to death become a serious concern. In battle, he is virtually invulnerable; only his eye is a "true" part of his body, with the rest instead being snow and ice that he has animated to serve as a physical form. This means that he can disperse and reform wherever he pleases, and instantly replaces any bodily mass lost to the blows of his foes. He can manipulate ice and snow to attack his foes, creating everything from flurries of rock-hard snowballs to jagged icicles and gale-force freezing winds laden with blinding snow.

Mu's only weakness is his eye, which can be destroyed with sufficient force, or a single Bakusai Tenketsu attack. Whilst even this does not permanently stop him, it does at least provide an opportunity for the Snow Girl to pacify him with her flute, which enables her to control him.