Tarō Tanaka serves as a member of the Miburo, the precursor group to the Shinsengumi, and holds the designation of one of its three wolves. Serizawa Kamo personally discovered Tanaka and recruited him into the organization. He shares the exact age as Chirinu Nio, the series' protagonist.

Prior to his recruitment, Tanaka endured significant hardships while laboring in multiple places of service. Surviving harsh treatment during this period profoundly shaped his outlook. These difficult experiences forged within him a powerful attachment to life and a heightened will to survive.