(Social Democratic Party). (1) The first Social Democratic party in Japan. The party was founded May 18, 1901, by Katayama Sen and Kotoku Denjiro and was immediately banned.
(2) A Japanese Social Democratic party that existed from December 1926 to July 1932, founded by right-wing reformers who had left Rodo Nominto (Labor-Farmer Party) in October 1926. In July 1931 some members of Shakai Minshuto joined the newly reestablished party Zenkoku Rono Taishuto (Labor-Farmer Masses Party). In July 1932, Shakai Taishuto (Social Mass Party) was organized as a result of the merger of Shakai Minshuto and Zenkoku Rono Taishuto.