Who was the first Japanese official to sign the surrender instrument aboard USS Missouri?

Mamoru Shigemitsu was the first Japanese official to sign the surrender instrument aboard USS Missouri.

Shigemitsu was Japan's foreign minister and signed at approximately 9:04 a.m. on September 2, 1945. He signed on behalf of the Emperor of Japan and the Japanese government, wearing formal diplomatic attire and using a prosthetic leg after losing his right leg in an earlier attack.

General Yoshijiro Umezu, chief of the Army General Staff, signed next at about 9:06 a.m. on behalf of Imperial General Headquarters. Their separate signatures represented both the civilian government and the Japanese military command.

Shigemitsu had also signed Japan's surrender to the Allies in a ceremony in Manila in 1945 before the final Tokyo Bay signing. After the war, he was convicted of war crimes but later returned to Japanese politics and again served as foreign minister during the early postwar period.