Which Japanese foreign minister signed the surrender instrument first on behalf of Japan?

Mamoru Shigemitsu signed the surrender instrument first on behalf of Japan.

Shigemitsu was Japan’s foreign minister when the formal surrender ceremony took place aboard USS Missouri on 2 September 1945. He signed on behalf of the emperor and the Japanese government at 9:04 a.m. Japan Standard Time. General Yoshijirō Umezu signed next for Japanese Imperial General Headquarters.

Shigemitsu had held major diplomatic posts before and during the war. He had also signed Japan’s surrender to the Allies in the ceremony while using a prosthetic leg, having lost part of his leg in an earlier assassination attempt. His role represented the civilian government, while Umezu represented the military command.

Several Japanese leaders are associated with the surrender process, which can cause confusion. Shigenori Tōgō was foreign minister during the final decision-making period but was not the first signatory at Missouri. Prime Minister Kantarō Suzuki headed the wartime cabinet but did not sign the instrument there.