Mamoru Shigemitsu was a Japanese diplomat and politician, best known for his role during World War II. He served as Japan's ambassador to the United States and later became the foreign minister. Shigemitsu was involved in negotiations that aimed to maintain peace between Japan and the United States before the war escalated. After Japan's defeat in 1945, Shigemitsu signed the Japanese Instrument of Surrender on behalf of the Japanese government. This act marked the official end of World War II for Japan. Following the war, he was tried for war crimes but was later released, continuing his career in public service.