The Shiranoi family has made a living for generations as exorcists by borrowing the power of an ayakashi, or spirit, that resides within a family sword. The protagonist, Kei Shiranoi, is the only daughter of the current head of the household, Riichi. In her childhood, Kei was unable to draw the sword, leading her father to reject her as unworthy of becoming the next family head. Her dream of following the family path as an exorcist was thus cut off, leaving a deep rift between father and daughter.

Years later, Kei returns home to find her father murdered and the family sword left beside him. The circumstances of his death force Kei to confront the secret her father had been hiding. The mystery behind Riichi's cold rejection and the true nature of the family's duty as exorcists begins to unravel. A one-shot version of the story gained significant attention, leading to a full serialization.

Driven by a desire to avenge her father and rescue his soul from an antagonist named Shuraku, Kei resolves to grow stronger. She seeks out the grand family head, Waketake Oukan, to train and unlock her own power. At Oukan's mansion, she encounters the powerful spirit Nyonajo, a major spirit from the Taisho era possessing a person named Jyonen. Facing an overwhelming gap in ability, Kei is pushed to her limits.

Simultaneously, the heads of various exorcist families gather to stop Shuraku's schemes, bringing their own sacrifices and resolve to the fight. As the conflict escalates, Riichi, who is being held captive, has his soul corrupted into a dark spirit by Shuraku. In response, the exorcist families each match up against powerful spirits from different eras. Kei, together with allies Mitsuya and Momowari, infiltrates an underground fighting arena where Kyomei, a major spirit from the Meiji era, holds sway. Kyomei's ability to amplify human aggression plunges the arena into chaos.

The central conflict culminates in the rebuilding of the bond between father and daughter, and a final confrontation with the true mastermind, Shuraku. The story weaves together family love, misunderstanding, the trials of inherited duty, and a battle to mend the past and secure the future.