Souichirou Senou, who is a rounin, discovers quickly that he is not trusted by most of his new neighbors in the Katagi Apartments. However, his childlike curiosity about the world around him helps him befriend Kankichi, the carpenter's son. With Kankichi's assistance, Souichirou manages to establish a new life in Edo's tenements by exchanging his long-time weapon, Kunifusa, for a bamboo blade, as he desires to avoid violence.
Despite his efforts to evade trouble in Edo, Souichirou soon realizes that it's not always feasible. He discovers that he is being stalked by the brutal assassin Shinnosuke Kikuchi, a man who revels in murdering anyone caught between him and his target. Every time Souichirou defends himself or the tenement dwellers, he is plagued by frightening memories from his past, and he is compelled to resurrect his younger days' bloodlust.
