Yasuko Fuzuchi belongs to the Fuzuchi family, guardians of a mountain shrine dedicated to a Sword God. She resides there with her family, including her brother Kuraki Fuzuchi, while her father serves as the head shaman and priest. During a rare purification festival occurring every 49 years, Yasuko encounters a visiting college theater group staying at her family's guesthouse. She corrects their initial misconception, informing members Takeo Nanachi and his friend that the ritual dancer they witnessed was her brother Kuraki, not a shrine maiden. The Fuzuchi lineage carries significant spiritual duties; Kuraki is destined to succeed their father as shaman and become the 15th master of a specialized sword technique preserved by their family. Yasuko's interactions with the visitors unfold within this ceremonial and domestic setting of the shrine and its guesthouse during the festival period.