Before revision: It is used in several ways: Political Sosai, or president of the government, was only once the title of the imperial prime minister: from 1 January 1868 (before there was no cabinet, only chief advisers: Kampaku to the nominally reigning emperor and both Rōjū and Tairō to the de facto ruling shōgun) until 11 June 1868: Prince Taruhito Arisugawa (1835–1895); next the prime ministerial office is styled U Daijin "Ministers to the Right", in 1871 shortened to Daijjin.
After revision: It is used in several ways: Political Sosai, or president of the government, was only once the title of the imperial prime minister: from 1 January 1868 (before there was no cabinet, only chief advisers: Kampaku to the nominally reigning emperor and both Rōjū and Tairō to the de facto ruling shōgun) until 11 June 1868: Prince Arisugawa Taruhito (1835–1895); next the prime ministerial office is styled U Daijin "Ministers to the Right", in 1871 shortened to Daijjin.