Story

Aoyama Yoshito, a university student studying folklore, becomes lost on a remote mountain while pursuing his lecturer. He discovers a secluded Western-style mansion belonging to the affluent Mikado family, a lineage of ancient nobility.

Yoshito is allowed to stay as a guest but must participate in the "Rite of Shadow Offering," a ceremony that will decide the next head of the Mikado clan. He navigates a complex situation involving the three Mikado sisters, other candidates, and the mansion's mysterious residents, uncovering dark secrets and traditions.