He was born in Hiuga. He graduated from Harvard in 1877, and entered the foreign office in Tokyo in 1884. He served as chargé d'affaires in Beijing, as Japanese minister in Seoul, in Washington, in St Petersburg, and in Beijing (during the Boxer trouble), earning in every post a high reputation for diplomatic ability. In 1901 he received the portfolio of foreign affairs, and held it throughout the course of the negotiations with Russia and the subsequent war (1904-5), being finally appointed by his sovereign to meet the Russian plenipotentiaries at Portsmouth, and subsequently the Chinese representatives in Beijing, on which occasions the Portsmouth treaty of September 1905 and the Peking treaty of November in the same year were concluded. For these services, and for negotiating the second Anglo-Japanese Alliance, he received the Japanese title of count and was made a K.C.B. by King Edward VII. He resigned his portfolio in 1906 and became privy councillor, from which post he was transferred to the embassy in London, but he returned to Tokyo in 1908 and resumed the portfolio of foreign affairs in the second Katsura cabinet.
It was in the early summer of 1905 that Baron JutaroKomura (afterward Count) arrived at the Waldorf-Astoria.
But now this much is known: that while Baron Komura was at first triumphantly planning for the conference, he was in-formed by the authorities at home that, in spite of Japan's almost unbroken string of military and naval victories, it was by no means sure of winning the war in a large sense.
Nulle saw Baron Komura there was a tense, solemn reticence about the man. Most of the time, however, he was shut up in his rooms, pouring out cable after cable in his frantic efforts to achieve a fairly triumphant treaty.