Operation PX , also known as " Cherry Blossoms at Night " , was proposed in December 1944 by the Japanese Naval General Staff , led by Vice-Admiral Jisaburō Ozawa . The name for the operation came from the Japanese use of the code name PX for Pestis bacillus-infected fleas . In planning the operation , the navy partnered with Lieutenant-General Shirō Ishii of Unit 731 , who had extensive experience on weaponizing pathogenic bacteria and human vulnerability to biological and chemical warfare
Unit 731
Unit 731
Operation PX