Houjou, Yukino

北条雪乃

She is the oldest Gate Keeper in Japan, born in 1169. However, she has ceased aging and appears in 1969 as a young girl wearing a white kimono. Ruriko and Shun first encountered her during their mission to retrieve a crashed plane and its cargo at Mt. Daisetsu in GK. As her name Yukino implies, she commands the Gate of Ice and Snow, enabling her to summon blizzards and hail. Yukino is also capable of teleportation and projecting visions that allow a person to witness a scene without physically being present. Reiji Kageyama labels her as the most powerful Gate Keeper in the series. One of her distinctive traits is that she speaks in Tanka poetry. Although she assists A.E.G.I.S. members, she is not an official member of the organization. She also keeps a pet ermine named Hisame. She is closest to Shun's sister, Saemi Ukiya.
Yukino reappeared in GK21, taking up residence at Tategami High and becoming the source of rumors about ghosts that emerge at night. Tragically, while her body has not aged, her powers and strength are finally waning, and she long ago stopped appearing before her old friend, Saemi. Recognizing a similar sadness in the daughter of an old friend, she helps and befriends Ayane and Miu.
The reason for her agelessness is explained in episode 5 of GK21. Gate Keepers typically have sad backgrounds because their gates absorb their happiness. Reiji Kageyama (Nazo) even mentions that gates used frequently can destroy a gatekeeper. In Yukino's case, she was summoning her gate constantly during emergencies, so her time was frozen due to overuse. She seemingly shared a close relationship with Reiji, discussing a promise they had made in one of the scenes in the OVA.
Although she suffered a fatal wound after her confrontation with Yuurei Shoujo in GK21 and her body dissipated into snow, she reappeared in the final scene to pick up Hisame, looking just as she used to.