After Japan occupied Manchuria in 1931, Ishii Shiro created Unit 731 and began testing biological weapons on unwilling human test subjects. The history of Imperial Japan’s human experiments was one in which Ishii and Unit 731 was the principal actor, but Unit 731 operated in a much larger context. The network in which 731 operated consisted of Unit 731 and all its sub-units, nearly every major Japanese university, as well as many people in Japan’s scientific and medical community, military hospitals, military and civilian laboratories, and the Japanese military as a whole. Japan’s racist ultra-nationalist movement heavily influenced these institutions and people; previous historians have failed to view Japan’s human experiments in this context. This thesis makes use of a combination of declassified United States government and military documents, including court documents and the interviews conducted during the Unit 731 Exhibition that traveled Japan in 1993 and 1994, and then recorded by Hal Gold in his book, Unit 731 Testimony, along with a number of secondary sources as supporting material. Each of these sources has informed this work and helped clarify that Unit 731 acted within a broader network of human experimentation and exploitation in a racist system, which normalized human atrocities. Attitudes of racism and superiority do not necessarily explain every action taken by Japanese military personnel and scientists, nor did every individual view their actions or the actions of their countrymen as morally correct, but it does help explain why these acts occurred. What enabled many Japanese scientists was the racist ideology of the ultra-nationalist movement in Japan.