Yuzu Hieda, a high school freshman, is the middle sister in a family of hereditary shrine maidens serving a Shinto shrine. She possesses significant mystical abilities yet displays worldly naivety. Her cousin, Tadahiro Amatsu, returns after years away; Yuzu harbors longstanding romantic feelings for him rooted in their shared childhood, including a promise made at the shrine.

When dark forces target Tadahiro due to his unique left eye that perceives the spirit world, Yuzu becomes his primary protector. Recognizing the escalating threat, she forms and leads the "Miko Council" (or "Priestess Club"), recruiting fellow female students to aid in his defense. Members include her enthusiastic best friend Seiko Rikiishi, sharp-tongued Chika Yurikasa, UFO-obsessed Izumi Sakibara, and demure wealthy girl Shizuka Midoh.

Yuzu undergoes rigorous training imposed by her eldest sister, Kurako Hieda, the shrine's head priestess and the group's mentor, whose methods are intensely disciplined. Yuzu wields a ceremonial dagger as her talisman, focusing her spiritual power for combat, with her signature attack named "white light beam." Despite her mystical role, she exhibits daily clumsiness, notably frequently colliding with people or obstacles on her bicycle, sometimes accidentally thwarting threats through these mishaps.

She balances normal high school experiences—friendships and school activities—with battling demons summoned by the sorcerer Michimune Ayatachi, who serves the dark god Yagarena. This conflict escalates with the emergence of rival Twilight Priestesses, spiritually empowered adversaries aligned with Yagarena. Throughout, Yuzu remains steadfast in protecting Tadahiro and confronting the supernatural threats, relying on her growing bond with the Miko Council.