Nanoka is transported to the Taisho era through a portal where she encounters Mao, an exorcist who saves her from a grotesque yokai but with some reluctance. Upon her return to the present, Nanoka realizes that she has gained new abilities and decides to venture back in time to find answers. However, her investigations lead her to Mao, who is investigating a string of heinous murders. As Nanoka searches for the truth about herself, she discovers that Mao and his sword are both cursed by a feline demon named Byoki, and anyone who handles the weapon suffers deadly consequences. Despite this, Nanoka chooses to take up the sword when Mao's life is in jeopardy.
