The Japanese occupation of Manchuria promised many opportunities for young scientists who wanted to utilize their training and curiosity to advance Japanese military capabilities. Recently graduated medical student Ishii Shiro seized this occasion, and with funding from the War Ministry of Imperial Japan, founded Unit 731, a biological and chemical warfare research and development arm of the IJA. With consent and funding from the military and government, he recruited the brightest minds from Japan to conduct fatal human experimentation, develop bubonic plague bombs to unleash on nearby villages, and test biological and chemical weapons.
Within a few years, he rapidly climbed the ranks, going from Captain to General for the Imperial Japanese Army. His impact and power overshadowed his European counterpart, Josef Mengele. After the war, he faked his death, but the CIA was able to locate him. However, he negotiated immunity and was never brought to justice in what came to be known as the elaborate American coverup of Japanese war crimes.
"General Ishii Shiro was working on a far greater scale than his German counterpart Josef Mengele. Compared to Ishii Shiro, Josef Mengele would have been only one of hundreds of similar workers in Unit 731, following orders. An example of the hypocrisy of the Allies following World War II is that they hunted Mengele down in the jungle like the animal he was. Yet many of the researchers of Unit 731 were professors of Japanese Universities and directors of Japanese medical companies and Ishii Shiro died in American occupied Japan fourteen years after the war."
Gregory Dean Byrd, Unit 731 Historian, in "General Ishii Shiro: His Legacy is That of Genius and Madman" (2005)