Giichi Tanaka, head of the Chosu Clan, was a Japanese military officer, statesman, and Prime Minister in 1929. After retiring from the military, he headed the Constitutionalist Party and supported party, rather than military or Emperor-centric, government. It is clear his cabinet resigned in 1929, but less clear if it was a protest over the assassination of Chang Tso-Lin, or a firing by Emperor Hirohito, displeased about party government. 
He was born in Yamaguchi, from a samurai family, loyal to the Chosu Clan. In 1892, he graduated from the Army War College, served in the First Sino-Japanese War, and studied in Russia in 1898. During the Russo-Japanese War, he was active as a staff officer of the Manchuria Army.
In 1909, he became chief of Army Affairs Section in the Ministry of War and established the Imperial Military Reserve Association (Teikoku Zaigo Gunjinkai) in 1910. The Association was not limited to military reservists, but was an expression of Tanaka's theory that "all citizens are soldiers" under the Emperor, and was principally focused on education. 
In 1911, he was promoted to director of the Military Affairs Bureau and recommended setting up two new divisions. In 1915, he became vice-chief of the Army General Staff and was involved in the Siberian Intervention. 
He traveled through China and Manchuria in 1917, producing a document called "The Exploitation of Chinese Resources".
High command and cabinet
In 1924, he and other Chosu, fighting a delaying action against the Satsuma Clan, compromised on accepting Army reforms in return for the fall of the Kiyoura cabinet, replacing it with that of Takaaki Kato. Afterward, he served as war minister in the Hara cabinet and the second Yamamoto cabinet. In 1921, he became an army general.
After the Army
After retiring from the army, he became president of the Seiyukai (Constitutional Government Party) and an Imperial nominee to the House of Peers, and became Prime Minister in 1927. During office he promoted the Shandong Expedition.
He was alleged to have created a Japanese plan for world domination, called the "Tanaka Memorial", in 1927. While Soviet Premier Nikita Khruschev warned Indonesia about it in 1960, it is believed to be a Soviet or possibly Chinese forgery. Bergamini offers the partial explanation that it was prepared by the Chinese, mixing notes of Tanaka and the Study Group of Teiichi Suzuki, creating a position not held by Japan. The Memorial, however, associated the Choshu-Constitutionalist group with imperialism,  although it also could be interpreted as a plea for economic development rather than conquest.
The purported text, which first appeared in Beijing in 1929, but was given new life by the Manchurian Incident, read
In the future, if we want to control China, we must first crush the United States just as in the past we had to fight in the Russo-Japanese War. But in order to conquer China we must first conquer Manchuria and Mongolia. In order to conquer the world, we must first conquer China. If we succeed in conquering China the rest of the Asiatic and South Sea countries will fear us and surrender to us. Then the world will realize that Eastern Asia is ours and will not dare to violate our rights. This is the plan left to us by Emperor Meiji, the success of which is essential to our national existence.
- David Bergamini (1971), Japan's Imperial Conspiracy, Morrow, p. 340
- Tanaka, Giichi, National Diet Library
- Herbert P. Bix (2001), Hirohito and the making of modern Japan, Harper Perennial, ISBN 978-0060931308, p. 208
- Richard Smethurst (1998), The Creation of the Imperial Military Reserve Association in Japan, in Peter Karsten, Recruiting, drafting, and enlisting: two sides of the raising of military forces, Routledge, ISBN 978-0815329756
- Merion and Susie Harris (1991), Soldiers of the Sun: the Rise and Fall of the Imperial Japanese Army, Random House, p. 121
- Bergamini, p. 356
- Harris, pp. 162-163
- Bergamini, p. 359
- Bergamini, p. 1101
- Merion and Susie Harris (1991), Soldiers of the Sun: the Rise and Fall of the Imperial Japanese Army, Random House, p. 162