Born to a Tosa samurai family, he won the confidence of Yamauchi Yodo and stood at the core of domain administration. Drawing on Sakamoto Ryoma's proposal, he drafted the memorial for the return of power to the emperor and persuaded domain lord Yodo to submit it to Shogun Tokugawa Yoshinobu (1867). This became the direct impetus for the Taisei Hokan and a turning point in the late Bakumatsu political situation. After the Meiji Restoration he joined the new government and held posts including State Councilor, Minister of Public Works, and Minister of Communications. Together with Itagaki Taisuke, who had resigned in the Political Crisis of 1873, he promoted the Freedom and People's Rights Movement and participated in submitting the memorial for an elected assembly (1874). He later formed the Constitutional Liberal Party and led the movement to open a national assembly. In his later years he served as Minister of Agriculture and Commerce in the Ito Hirobumi cabinet. His practical ability and skill at coordination were highly regarded, and as a Tosa-born politician he continued to play an important role consistently from the Bakumatsu through the Meiji era. He died on August 4, 1897, at fifty-nine. His contribution to the Taisei Hokan is one of the greatest gifts Tosa gave to modern Japan, alongside those of Sakamoto Ryoma and Nakaoka Shintaro.

Practical and a skilled negotiator, he had the ability to translate Ryoma's ideas into concrete politics. His persuasive power with domain lord Yodo was notable, and he excelled as a mediator bridging idealism and reality.

By drafting the memorial for the Taisei Hokan he played a decisive role at the most important juncture in Bakumatsu politics. His participation in the Freedom and People's Rights Movement contributed to the development of Meiji democracy, and together with Itagaki Taisuke he is sometimes called one of the twin pillars of the Tosa civil rights faction.