Yaya Yuiki (結木やや, Yuiki Yaya) is a character in Shugo Chara. Yuiki is the childish girl serving as the Ace's Chair and is one year junior to Amu. Yaya often acts immature for her age, such as having an enormous sweet tooth, a great soft spot for items like ribbons as well as tending to be hyperactive. Yaya wants to be a baby forever so her parents would give her more love than her younger brother. She is also a good ballerina, but also a rather clumsy one. Yaya's favorite things are cute and babyish.
She is voiced by Tomoko Nakamura.
Yaya wears her hair in pigtails with big red ribbons attached to her hair. Her eyes are brown and her hair is orange/brown. Like the other female Guardians, she wears a red cape at school.