The series follows Nanoka Kiba, a modern middle-school girl who time-travels via a shopping arcade portal to the Taisho era. There she joins the cursed onmyoji Mao in battling yokai and investigating murders tied to curses from clans such as Goko and Goshikido.

Concrete supernatural plots include the Spider Lady murder case, infiltration of the Shorinkyo cult, keystone earthquakes, Byoki's abduction, Hyakka's fire sorcery attacks, and the Taizanfukun spell. These elements draw directly from onmyodo folklore, shikigami, and historical settings. The narrative maintains full consistency with its Japanese source material through an all-Japanese voice cast and characters that align with both Taisho-era and contemporary contexts.

Time-travel and curse plots operate strictly according to folklore mechanics rather than any identity or systemic themes. This approach avoids modern activist framing entirely, keeping the focus on supernatural investigation and clan rivalries without introducing social commentary or progressive messaging.