Surgeon General Shirō Ishii (Japanese: 石井 四郎, Hepburn: Ishii Shirō; [iɕiː ɕiɾoː]; 25 June 1892 – 9 October 1959) was a Japanese biological weapons specialist, microbiologist and army medical officer who served as the director of Unit 731, the largest biological warfare and chemical warfare unit of the Imperial Japanese Army.

Ishii led the development and application of biological weapons at Unit 731 in the puppet state of Manchukuo during the Second Sino-Japanese War from 1937 to 1945. This included the Battle of Changde, the Kaimingjie germ weapon attack, and the planned Operation Cherry Blossoms at Night biological attack against the United States, which intended to spread a weaponized bubonic plague. Ishii and his colleagues also engaged in human experimentation, resulting in the deaths of thousands of subjects, most of them civilians or prisoners of war.

Ishii was later granted immunity in the International Military Tribunal for the Far East by the United States government in exchange for information and research for the U.S. biological warfare program.

https://en.wikipedia.org/wiki/Shirō_Ishii