The Shogun's Vault IV: The Gold Mines of Sado

Account magistrate Wakisaka Bizen Mamoru enlists Yoshibei, the chief priest of Iriya and Myohoji Temple, to investigate the Sado Gold Mine, suspecting that substantial funds are being diverted to an undisclosed destination. Yoshibei, a former top-secret official, accepts the assignment and recruits three skilled Karadogumi: Nanikiri, Hayashi, and Kumonryo. In Sado, the four infiltrate, while magistrate Okubo Hitachi Mamoru, who plans to overthrow the shogunate, seeks to purchase a large consignment of firearms from Russia.