Businessman. Born in Kyoto as the eldest son of Takayoshi Mitsui. In 1872, he went to the United States with five other children of the Mitsui Family to study. After returning to Japan, he engaged in various businesses controlled by the Mitsui Family. In 1887, he became head of the Family. In 1892, he became president when the mining business of Mitsui was organized into an unlimited partnership. From then on, he devoted himself to the family's mining business, the construction of Miike Harbor and other projects.