[1] Komura was born to a lower-ranking samurai family in the service of the Obi Domain in Kyushu's Hyūga Province (now Nichinan, Miyazaki Prefecture).

While at Harvard, Kaneko and Komura visited the home of Alexander Graham Bell and spoke on an experimental telephone with a fellow Japanese student, Izawa Shunji.

In that position, he conveyed to the Chinese government Japan's intention of dispatching troops to Korea under the provisions of the Treaty of Tientsin to subdue the Tonghak Rebellion, which led to the First Sino-Japanese War.

"[8] The war was ended with Komura's signature on behalf of the Japanese government of the Treaty of Portsmouth, which was highly unpopular in Japan and led to the Hibiya incendiary incident.

Komura also met with Chinese representatives in Beijing and signed the Peking Treaty of December 1905, which transferred the former Russian rights in southern Manchuria to Japan.

Suffering from tuberculosis in his final years, Komura moved to the seaside resort of Hayama in Kanagawa Prefecture, but he died of the disease on November 26, 1911.

In Ryōtarō Shiba's semi-historical work Saka no Ue no Kumo, Komura inherited massive debts from his father, which he had difficulty with repayment.

That, combined with his short stature and a large mustache, led to the derisive nickname of "the rat minister" in the diplomatic community in his early career.