Chizuru Yukimura, daughter of Kodo Yukimura—a physician commissioned by the Shogunate to create the Water of Life elixir—embarks on a perilous path when her father vanishes. The elixir, designed to enhance strength and healing, carries a dire cost: users risk becoming Furies, ravenous entities consumed by violent frenzy. Disguised as a man, she ventures to Kyoto to trace Kodo’s footsteps, only to cross paths with the Shinsengumi after witnessing a Fury’s rampage. Mistaken for a spy, she is detained but secures her place among them by disclosing her ties to Kodo’s research.

A latent healing power, dormant since childhood, surfaces when she inadvertently quells Keisuke Sanan, a Shinsengumi captain corrupted by the elixir. This act exposes her extraordinary physiology, later traced to her Oni lineage—a heritage unveiled by Chikage Kazama, a pureblood Oni leader intent on drawing her into his clan’s war against humanity.

As the Shinsengumi grapples with the Water of Life’s toll, Chizuru confronts the moral decay and physical unraveling of allies like Toshizo Hijikata, who embraces Fury transformation to defend their cause. Betrayals fracture trust, including Kaoru Nagumo’s collusion with Kodo’s radical plot to forge a Fury army and overthrow the government. Despite her father’s manipulations and the Shinsengumi’s waning influence in the Boshin War, Chizuru clings to loyalty, standing beside Hijikata as political collapse looms.

Her evolution from an earnest seeker to a resolute mediator between human and demon realms hinges on clashes with allies and enemies alike. Confronting her dual identity, she balances empathy for comrades with wartime brutality. Revelations of her ancestry and Kodo’s destructive legacy steel her resolve to shield those she values, driving her to shape pivotal conflicts and decisions that seal the Shinsengumi’s fate.