Yuki is a minor character in The King of Fighters series. She is a normal school girl as well as Sie Kensou's lover.
On her way to the last date she'd have with Kusanagi prior to King of Fighters '97, Yashiro and his teammates Chris and Shermie (whom she briefly met some time ago in a TV station) kidnapped her with intentions of using her as a sacrifice for Orochi's resurrection. Her heritage as the last sacrificial maiden of their lord was a necessity for his physical body to come into being. The Three Sacred Treasures Team (Kyo, Iori, and Chizuru) has would foil this plan by interrupting the process early, forcing Orochi to possess the body of Chris. However, Yuki is left unaware of her involvement and is still ignorant of the history of her family line.
Despite fan theories of her death at the end of King of Fighters '97, Yuki has survived the ordeal and continues her normal life in Japan. During the NESTS saga, she is also remains unaware of NESTS involvement with Kyo or the reasons for his disappearance. While she was ironically saved by Iori from being kidnapped by NESTS's minions. Kyo's teammate and friend, Benimaru often chides Kyo for his negligence in contacting Yuki, though they both understand that it was needed to protect her.
In KOF: Maximum Impact 2, Kyo tries to keep in touch with her through phone booths scattered around South Town.
Personality-wise, Yuki is pretty much the 'girl next door' type. She is a calm, polite, and patient lady who sees the best in her boyfriend, even if he gets embarrassed by what she sees. Though she can get slightly annoyed by his reluctance to study for classes, as well as she genuinely worries for his safety and faithfully waits for his return when he disappears from Japan. In the series' drama CDs, they went on a date before the '97 tournament and she buys him an amulet, which Kyo continues to treasure when they're apart from one another.