In the secluded mountain village, Mamoru and his onee-chan Kotone, survivors of a devastating fire from years ago, have found shelter with the Kamishiro family. Now servants in the headman Kojiro's household, they face the impending Feast, a longstanding custom meant to address the village's low birth rates by involving the family's women. Kotone, embraced as the eldest daughter, accepts her role out of deep gratitude and responsibility toward her benefactors. Meanwhile, Mamoru, aware of the tradition's demands, chooses to support the proceedings despite his inner turmoil, as the event draws near.