It has been several centuries since human population has declined. Food has become harder to find and what little sources the humans have are considered highly valuable. The most prosperous species on the Earth are “Fairies”, 10 cm tall creatures with high intelligence and a great love for sweets. A nameless girl, the main character, became a UN arbitrator between the humans and the fairies and had returned to her hometown to help her grandfather. One day, the village is sent some strange products made by a company called FairyCo. Since the villagers are wary of using the products, the girl, her grandfather, and a nameless boy decide to go to the factory to find out about the mysterious products and who is behind making them.The story is set several centuries into the slow decline of mankind. Earth has now become the realm of “fairies” — 10-centimetre-tall creatures with remarkable intelligence and an appetite for sweets. The human protagonist of the story serves an important duty as the international arbitrator between the fairies and humans, and she returns to her former hometown of Kusunoki. She chose this job because she thought it was an easy job she can do, even when she is as old as her grandfather. However, she learns that her job is anything but simple when she meets the fairies.