Botan, a shikigami forged by the Abe clan six centuries ago to imprison the demonic serpent Orochi, fulfilled her purpose alongside warriors Kagemitsu and Hirari. To shield Hirari from their shared trauma, she stripped his memories of their victory, pledging to await their reunion across lifetimes. Centuries passed as Hirari reincarnated, haunted by fragmented dreams of her, while she lingered in solitude.

By the Meiji era, she masquerades as a schoolteacher, covertly assisting the Kumō brothers in apprehending criminals. Her carefully guarded detachment wavers when Hirari’s reincarnation starts unraveling their forgotten history, though she deflects his inquiries, coldly asserting her identity as an emotionless instrument bound to duty.

The Orochi’s resurgence forces a climactic battle, where its awakening nearly annihilates her. Hirari, now restored to his past-life memories, risks everything to shield her, rekindling their ancient bond. In the aftermath, she tentatively voices a wish to see Oumi bathed in sunlight—a metaphor for her fragile acceptance of transient human joys.

Prequels set three centuries prior delve into her earlier struggles against the Orochi’s influence and alliances with historical figures tied to its curse. These tales underscore the toll of her immortality, juxtaposing her stoic resolve with flickers of unresolved grief.

Her journey evolves from unwavering obedience to her creators into a quiet reckoning with lingering human ties, culminating in Hirari’s steadfast devotion bridging six hundred years of silence and fulfilling their fractured oath.