Kato, Tomosaburo (tōmōsˌäˌbōrōˈ, käˈtō) [key], 1861–1923, Japanese admiral. He was naval chief of staff (1894–95) and chief assistant to Admiral Togo in the Russo-Japanese War. As navy minister from 1915 to 1923, he directed Japanese naval operations in World War I and the naval expansion thereafter. At the Washington Conference (1921–22) he accepted the principle of naval limitation. He was prime minister (1922–23).