Absolute Anime

Yaya Yuiki is the youngest of the Seiyo Guardians, a fourth grader. She has a new-born baby brother Tsubasa who she claims gets all her parents attention. Her Guardian Chara is a baby named Pepe and her Chara Change is activated with the phrase "Pretty! Cutie! Love baby!" Yuiki also acts very babyish, her Chara Attack is Giant Rattle Attack (first seen in Episode 6).

Yuiki takes ballet. In Episode 6 the prima donna, Himekawa Maika, sprains her ankle and is unable to perform. Yuiki is asked to take her place. Kukai Souma teases her by saying he thought she'd be a rock or tree. After Amu cleanses the X Chara, the Guardians see Yuiki's performance. Souma is crying and says he never thought he'd cheer on Yuiki as a prima. Maika tells Yuiki she had made a mistake in the second act, but she had done well.

Yuiki has a close relationship with Kukai Souma and might have a crush on him. She is usually seen hugging, standing by, or arguing with him.

Yaya's dream is to grow up to be a baby, and she always has to speak in 'baby-talk' by calling people '-chi' or '-tan', as well as referring to herself in 3rd person a lot of the time (an example being when she transforms, rather than saying "My Heart" she says "Yaya's heart".