A young girl named Kiharu comes from a small village known for its stunning blue-green feathered messenger birds. She owns her own bird, Popo, which she controls using a Walnut Stone flute. Despite her love for these magnificent creatures, Kiharu harbors deep resentment towards the nobles who have carelessly hunted them and disregarded the island's inhabitants. Driven by her anger, she travels to Clarines to voice her concerns, only to find herself facing a series of trials.