The Unit 731 museum in Harbin has released a previously unseen, 47‑minute interview with a former member of the Japanese imperial army’s biological warfare program, providing a rare firsthand account of how plague was transformed into a weapon. The interviewee, identified in wartime rosters as Sato Hideo and described as a member of the Takahashi detachment (the “plague unit”), recounts dissecting more than a thousand infected animals and conducting experiments intended to quantify lethality and transmission.
Sato describes small mammals—mainly guinea pigs and rodents—systematically infected and autopsied, noting heavy congestion of the lungs and blackened, enlarged organs. He states plainly that the unit’s research goal was to weaponize Yersinia pestis, and that animal experiments were used both to measure dose‑response and to test propagation methods that would turn a pathogen into a battlefield agent.
The testimony also reconstructs an industrial process: climate‑controlled “greenhouses” with incubators and stainless steel culture tanks used to grow bacteria at set temperatures for 24–48 hours, and a production line sufficient to generate what a postwar witness later testified was roughly 300 kilograms of plague per month and up to a ton of anthrax. Sato says cultures were loaded into bombs and disseminated by aircraft, while other unit personnel bred fleas on rats to serve as vectorized delivery systems—an account that ties laboratory practice to battlefield dissemination.
This release matters because it stitches together technical details and operational intent that historians and survivors have long alleged but that postwar legal and political settlement left partially unresolved. Evidence of Unit 731’s experiments and field use surfaced in wartime Soviet prosecutions and in later scholarship, but many alleged perpetrators avoided criminal conviction; some were reportedly granted de facto immunity by U.S. occupation authorities in exchange for data. A contemporary, self‑contained confession recorded by a Japanese scholar provides fresh documentary weight to the historical record.
Beyond the archival value, the testimony has present‑day implications. It reinforces the taboo against biological weapons, underscores the humanitarian horror of human experimentation, and feeds ongoing Sino‑Japanese tensions over wartime memory and responsibility. For policy makers and scientists, the record is a reminder of the dangers at the intersection of high‑throughput microbiology and military intent, and of the need for transparent historical reckoning, robust biosecurity safeguards and international mechanisms to deter and investigate misuse.