Promoted to colonel in 1930, Tanaka took command of the 2nd Infantry Regiment. He was military attaché in the United States in 1932 and chief of staff of the 4th Division in 1934. After becoming a major general, he took command of the 5th Infantry Brigade in 1935. The next year, he was appointed chief of the General Affairs Division in the Military Police Headquarters.
In 1937, Tanaka commanded the Guandong Military Police Command; he was promoted to lieutenant general and headed the Military Police Command the following year. In charge of the 13th Division in China in 1939 during the Sino-Japanese War, he was engaged in defensive operations in central China. One year later, he again headed the Military Police Command. He led the East Army in 1941 and the Fourteenth Army in 1942, endeavoring to maintain public order in the Philippines.
As a full general in 1943, Tanaka was assigned to the General Staff but without a specific post in deference to his health problems. He became director of the Army War College in 1944 and was, in addition, military counselor for the emperor. As Twelfth Area Army commander from March 1945, he was responsible for the defense of central Honshu Island, including Tokyo and the Imperial Palace.
In August 1945, Emperor Hirohito was determined to surrender to the Allied powers, but prominent Japanese military leaders opposed such a step. Tanaka worked hard to persuade these leaders to accept a peace and helped to foil a coup d'état. He then committed suicide in Tokyo on 24 August, taking personal responsibility for the surrender.
Frank, Richard B. Downfall: The End of the Imperial Japanese Empire. New York: Random House, 1999.; Tsukamoto Kiyoshi. Ah Kogun Saigo no Hi (The last days of the Imperial Army). Tokyo: Shuppan Kyodo-Sha, 1953.