Reon, a middle school boy, moves to Tsukito Island after his mother dies. The island is a small, isolated community where his mother was born. There he reunites with his childhood friend Rinko, the daughter of the island’s richest family, who is an apprentice shrine maiden of the Shuto family. Rinko possesses supernatural powers, most notably the ability to fly, which amazes Reon. However, their rekindled friendship takes a turn when Rinko makes a shocking confession: as the island’s shrine maiden, she is bound to the island by a curse—she cannot leave Tsukito Island, or she will die. Reon is deeply affected and vows to find a way to break her fate and take her to Tokyo, as he had promised when they were young.

The story unfolds on Tsukito Island, a place steeped in tradition and mystery. The island’s inhabitants are generally friendly toward Reon but remain wary of outsiders. The local folklore and the history of the gods are central to the conflict. A talking clay figurine appears, and during the island’s evening festival, an incident occurs that leads Reon to meet someone linked to the island’s deeper secrets. Rinko’s aunt Risako, who died trying to leave the island and became a taboo figure, returns as a spirit inhabiting a rabbit‑shaped clay figure, stirring up trouble while also hinting at dangerous truths. Later, a mysterious girl named Metori arrives, claiming to monitor the moon rabbit, and the true purpose of Risako—who was sealed away by the island’s ritual—comes to light. Reon pursues the key to breaking the curse, the Moon Rabbit Kaitai no Sho, which appears in an unexpected form. Meanwhile, Rinko herself begins to experience changes. As mysteries compound, the boy and girl face the island’s ancient history and the gods’ legacy.