Set in Edo-period Japan, the story follows Kyojiro Tatewaki — a young doctor beloved by the people of Edo for his gentle, healing presence. Beneath that reputation is a secret: he is also an assassin, delivering the justice that the law cannot or will not reach. By day he saves lives; by night he ends the right ones. Operating under the guidance of his adoptive father Dojun and alongside fellow assassins, Kyojiro walks a line between healer and executioner as corruption tightens its grip on the city.