A lower-ranking samurai of the Satsuma domain, he was recognised by his lord Nariakira Shimazu. He brought about the Satsuma–Choshu alliance (1866) and the restoration of imperial rule (1867). He led the Boshin War and achieved the bloodless surrender of Edo Castle. After a period back in Satsuma he returned to the new government in 1871, but came into conflict with Toshimichi Okubo and others over the question of Korea. He went back to Satsuma again and founded a private school, occupying himself with teaching; but in 1877 the Satsuma Rebellion broke out, and after defeat he took his own life at Shiroyama. As if to reflect that stormy life, his calligraphy is marked by an upright, bold manner.