One of several yōkai created in the mountains of northern Japan, Yukime (ゆきめ/雪姫) is a 16-year old yuki-onna whose life and existence was complicated due to her love and emotions for Nūbē. The connection was originally made five years prior, when the spiritualist, then a college student lost while skiing in the mountains, saves the young girl yōkai from a hunter determined to kill her before she grows up to bewitch and harm his village.

After Nūbē saved her life, Yukime made a promise that she would eventually find him so they could be together "in eternal love". The meaning of this was eventually made clear when she came down to Doumori, intent on bringing home her beloved Nūbē... frozen in ice where he would not die, to live with her "for eternity". She still has a warm heart, however, and her love for Nūbē was real, and Yukime was convinced that he shouldn't be brought to the mountains thanks to the efforts of Nūbē's students; when she tried to attack them, the until-then frozen Nūbē de-froze himself and told Yukime that she should leave, and so she did... for some time, since she returned and decided to stay in Domori, working as an ice skating coach at the local skating rink and trying to win his heart.

Due to being a yuki-onna, Yukime possesses several powers and weaknesses due to her connections with snow, ice and the cold. Yukime's main ability is the creation of snow or ice from her body, using it as a means to freeze any target she can see or point at. Her freezing power is useful in offensive attacks, the creation of roadblocks to stop larger targets, and even can be used to concentrate light like a magnifying glass. (not to mention its useful for making shaved ice, which according to Nūbē is the only good thing Yukime's power is for) Yukime also possesses a slight healing ability and, due to her cold connections, has a natural talent for figure skating.

Unfortunately, being a yōkai of snow has its weaknesses: she can not stand intense heat and can only remedy certain areas by freezing an area to a much colder, more tolerable temperature. Furthermore, Yukime can not make hot foods nor can she wear certain black clothing for fear of melting certain parts of her body. But Yukime does have a cute remedy for temperature problems: when she becomes too hot, she wraps her entire body into a snowman to cool herself down, and can drive Nūbē crazy when she pops out of it... completely naked. While many of these heat problems were eventually remedied through a revival later in the series, Yukime does occasionally still have problems with hotter temperatures.

While Yukime becomes a valuable ally and nuisance in Doumori, it is her relationship situations involving her and Nūbē that drives most of her character through the series. After her first appearance as a "yōkai of the chapter", she eventually holds a love/hate relationship with the teacher, with several attempts by the yuki-onna to get Nūbē to fall for her leading to some acknowledegment, but further frustration for both of them. Making matters worse is beautiful and ultra-sensitive Ritsuko-sensei, whom Nūbē originally desires and whom eventually begins to return some of her feelings just as Yukime is starting to get through to him.

The tension builds to a breaking point when another of the Mountain God's servants tricks Yukime into capturing the teacher, making her believe that Ritsuko's sacrifice is needed to make her human and win over Nūbē. When Yukime tried to kill kill Ritsuko-sensei and ultimately failed, believing that Ritsuko had no fault and that it wasn't fair to injure her, the youkai told Yukime that he was simply sent to test if she still possesses the cold yuki-onna's heart and bring her back to the mountains if she does, or kill her if she had indeed sympathized with humans.

Nūbē finally came to save Ritsuko-sensei and Yukime, and after saving Ritsuko he apologizes to her and admits his love for the latter. It was too late, however, as a severely injured Yukime used the last of her powers to help destroy the youkai and turned into snowflakes in Nūbē's arms. As Miki and Hiroshi cried, Kyouko asked Ritsuko if Yukime was truly dead, and she told her that she probably wasn't and that her snowflakes might allow her to be reborn later.

While Nūbē believed her to be dead, Yukime was, in fact, not. Like Ritsuko said, Yukime's snowflakes were carried away to her mountains, where the Mountain God used them to create another yuki-onna in her place, with the exact same looks and the exact same name. This Yukime, however, had a cold heart and did not hesitate to kill a human. Nūbē found her during a winter school trip, where she tricked him away from his class in order to kill him. He allowed her to attack him, but not without invoking fragments of the original Yukime's memories and fragments of her warm heart. Confused, the "new" Yukime fled without killing Nūbē and his class.

Yukime returned to Doumori later to find closure to her conflicting feelings, and realizing she did love Nūbē, decided to stay and reconcile the two halves of herself. Although she did not remember much of her life before, it was implied that Yukime eventually recovered all of her memories. Her personality was also changed from the aggressive yuki-onna youkai to a balance between her childish former self and assertive new identity.

In the anime, there was an alternate world created in Kyouko's dreams and subconscious, created by a youkai that had possessed her in her sleep. In that alternate world, Yukime had grown into a full-fledged yuki-onna and still was at Doumori, but she wasn't with Nūbē anymore since he was in a catatonic state after being almost murdered by another youkai. (note: although the chapter existed in the manga, Yukime was not in the original chapter since she had yet to return to Dōmori at this time) Source - Wikipedia