Loving this story, great first chapter. I can see this developing in multiple ways.
A. Aya time travelled.
It was stated that aya papaya likes to wander so maybe she went dora explora and found some way to time travel (IE. walking through a tunnel, finding a door, or picking up/ already possessing an object that gives her said power. My muns on her ring-a-ding charm bracelet.)
B. She was killed in some way? murder most likely, either day or day of the festival, and is a spirit but i kinda doubt that based on a hunch.
C. Aya isn’t human.
Maybe she is some yokai or mythical creature and likes to mess with humans? She was stated and seems to have a playful and mischevious personality and dipped out when things got a little too serious?
What do you guys think?