World War II Database

Contributor: C. Peter Chen

ww2dbaseYoshio Hareyama became the first scientific head of OKA 9420 of the Epidemic Prevention and Water Purification Department (Unit 731) of the Japanese Southern Expeditionary Army Group, headquartered in Outram Park, Singapore (now the building hosting the Singapore Ministry of Health). He held that post for only a brief period of time in 1942. His primary task was to prevent the spread of tropical diseases among Japanese military personnel. While some accused Unit 9420 of weaponizing diseases such as Bubonic plague during the war, it was unknown whether this work began during Hareyama's brief reign.