In 1932, Surgeon General Shirō Ishii (石井四郎, Ishii Shirō), chief medical officer of the Imperial Japanese Army and protégé of Army Minister Sadao Araki was placed in a command of the Army Epidemic Prevention Research Laboratory (AEPRL).
Ishii organized a secret research group, the "Tōgō Unit", for various chemical and biological experimentation in Manchuria.
Ishii had proposed the creation of a Japanese biological and chemical research unit in 1930, after a two-year study trip abroad, on the grounds that Western powers were developing their own programs.

One of Ishii's main supporters inside the army was Colonel Chikahiko Koizumi, who later became Japan's Health Minister from 1941 to 1945.
Koizumi had joined a secret poison gas research committee in 1915, during World War I, when he and other Imperial Japanese Army officers became impressed by the successful German use of chlorine gas at the Second Battle of Ypres, in which the Allies suffered 5,000 deaths and 15,000 wounded as a result of the chemical attack.
In 1932, Surgeon General Shirō Ishii (石井四郎, Ishii Shirō), chief medical officer of the Imperial Japanese Army and protégé of Army Minister Sadao Araki was placed in a command of the Army Epidemic Prevention Research Laboratory (AEPRL). Ishii organized a secret research group, the "Tōgō Unit", for various chemical and biological experimentation in Manchuria. Ishii had proposed the creation of a Japanese biological and chemical research unit in 1930, after a two-year study trip abroad, on the grounds that Western powers were developing their own programs.
One of Ishii's main supporters inside the army was Colonel Chikahiko Koizumi, who later became Japan's Health Minister from 1941 to 1945. Koizumi had joined a secret poison gas research committee in 1915, during World War I, when he and other Imperial Japanese Army officers became impressed by the successful German use of chlorine gas at the Second Battle of Ypres, in which the Allies suffered 5,000 deaths and 15,000 wounded as a result of the chemical attack.
Unit 731