A long time ago, Aya was only known as Project Z. A soulless girl with no mind of her own, only existing to fulfill the orders of the organization in their crusade against SEES. A puppet, nothing else.

However, that changed when Kurisu Tokuro and Zero Kisaragi(in a conflict with the other self in his body which had the control temporarily, the Fallen) came to battle Nyx. Nyx made Z her slave to fight Kurisu and Zero alongside her. Nyx intended to lose after testing Kurisu’s will in particular, yet the fight was brutal, as Z was specifically designed to nullify Zero’s abilities. But, in the end, Nyx’ gambit was successful, with Kurisu receiving the power of Fate Weaving and changing both Nyx’ fate, turning her into who she originally was, and Project Z’s fate, causing the girl to attain a soul and mind. They brought her to the Teahouse, where she lived from then as Aya - short for Ayatsuri, which roughly equals to “puppet”. Zero is not exactly the greatest with names. After a while, the girl showed tremendous skill in everything about crafting, causing Kurisu to give her an own workshop next to the Teahouse. She now regularly makes repairs and designs new decorations for the building.