A native of Hyōgo prefecture, Tanaka graduated from the 19th class of the IJA Academy and 28th class of the Army Staff College. He then went on to earn a degree in English literature at Oxford University where he studied the works of William Shakespeare. He led the Japanese troops in London’s victory parade at the end of World War I.

From 1930-1932, he was commander of the IJA 2nd Infantry Regiment. Tanaka was subsequently posted as a military attaché to Washington D.C., where he met Douglas MacArthur while MacArthur was Chief of Staff of the United States Army.

As a result of his long service in the United States and United Kingdom, and his openly pro-western sentiments he was passed over for promotions as Japan militarized. From 1934-1935, Tanaka was Chief of Staff of the IJA 4th Division.

With the start of the Second Sino-Japanese War, Tanaka was as‌signed to the IJA 5th Infantry Brigade, and was at the 1938 Battle of Wuhan. He was recalled to Japan shortly thereafter and appointed head of the Kempeitai (military police arm of the Imperial Japanese Army), in the Kantō region. He returned to China as commander of the IJA 13th Division from 1939-1940.

At the start of the Pacific War, Tanaka was commander in Chief of the Eastern District Army, and was later as‌signed administrative positions within the General Staff.

On May 28, 1943, Tanaka was relieved by Shigenori Kuroda as Military-Governor of the Philippines when promoted to full general.

He was forced to return to Japan in early 1944 to recover from malaria.

Tanaka was hailed a hero in his homeland in the August 15, 1945 incident where he aborted a rebellion planned by Major Kenji Hatanaka and others. Hatanaka sought to occupy the Imperial Palace, and to prevent the Emperor’s announcement of Japan’s surrender to the Allied Forces from being broadcast.

Tanaka felt responsible for the damage done to Tokyo (his jurisdiction) by Allied bombing. He had attempted to resign three times, after he failed to prevent damage to Meiji Shrine, the Imperial Palace, and other important sites, but his resignations were refused. After the war, Tanaka told his subordinates to destroy the unit colors, but not to commit suicide; burning the regiment’s banners would be enough payment, he said.

On August 24, 1945 at his office in Tokyo’s Dai-ichi Life Building (later Supreme Commander for the Allied Powers headquarters), Tanaka shot himself through the heart; he left his desk covered in sutras, letters to his officers and his family, a statue of Emperor Meiji and a scroll bearing Emperor Hirohito’s words to him following the August 15th incident.

Shizuichi Tanaka committed suicide on behalf of all his men.