Aya is a character who lives alone in the mountain forest, crafting letter carriers for Mushishi. Aya has dark eyes and wears her hair short, with her bangs brushed to her right. She wears dull kimono and has a rather disheveled appearance after the disappearance of Ito. As a child, she wore her hair long, although, before her apprenticeship, she kept it tied in a bun behind her head. She also wore colorful and patterned kimonos. Aya is very family-oriented. She enjoys learning about her family's traditional crafts. Despite her fear, she resolves to go with the elder even without Ito, and will not let Ito go alone. At two years old, Aya and her sister, Ito, are tested for the ability to see Mushi, as is the custom in their family. Both can see the uro that the elder had in a jar, so he determines that when they are 10, he will return to take one of the girls as an apprentice. At 10, the head of the family decides that they'll be lonely apart, and send both Aya and Ito away.

Spoiler

When Ito disappears, Aya blames herself for lifting the sheet that fell over her sister, and her mourning continues after the elder tells her it is not her fault, even after his death and for five years following Ito's disappearance. Aya searches for her sister and places letters into the empty cocoons, hoping to find her. In this time, Aya stops wearing the colorful kimonos of her childhood and cuts her hair.

(Source: Mushishi Wiki, edited)