From Tosa to the Meiji government
Born into an upper-ranking samurai family in Kochi, Itagaki originally bore the surname Inui. He held domain offices, joined the anti-shogunate coalition and commanded Tosa troops in the Boshin War of 1868. He subsequently took part in domain reform and, as a government councillor from 1871, helped advance the abolition of domains.
Itagaki served in the caretaker government during the Iwakura Mission. In 1873 he supported Saigo Takamori's proposed mission to Korea and resigned after the dispute over Korean policy. Petitioning and political associations then became central to his work outside the government.
Petitioning and institutional negotiation
In 1874 Itagaki and other former officials signed a petition for a popularly elected assembly. The document attacked domination by a small official elite and linked taxpayers' obligations to participation in government. Against the claim that the population was insufficiently educated, it argued that participation itself could develop knowledge and public responsibility.
Itagaki also helped establish political associations including the Aikoku Koto and Risshisha. At the Osaka Conference in 1875, intermediaries brought him together with Kido Takayoshi and Okubo Toshimichi to negotiate institutions including a Senate, a conference of local officials and a supreme court.
Party leadership and later public work
Itagaki became president of the Liberal Party in 1881. The party used newspapers, speeches and local networks to press for constitutional government, but faced restrictions and internal divisions before dissolving in 1884. He survived an attack in Gifu in 1882 and subsequently travelled to Europe with Goto Shojiro.
After the Imperial Diet opened, he continued party work without becoming a member of the House of Representatives. He served as home minister in 1896 and again in Okuma Shigenobu's cabinet in 1898. His later public interests included relief for workers and farmers, family life and social policy. He died in 1919.