Former Unit 731 Member Confirms Japanese Military Buried Poison Gas Shells in China

A former member of Japan’s notorious Unit 731 has confirmed in a 70-minute oral testimony that the Japanese military buried large quantities of poison gas shells in China before Japan’s defeat in World War II, according to Xinhua News. The testimony provides rare perpetrator-side evidence about the extent of Japan’s chemical warfare operations in China and adds to the historical record of wartime atrocities committed by Japanese forces.

The disclosure was made on August 12 by the Exhibition Hall of Evidence of Crimes Committed by Unit 731 of the Japanese Imperial Army, which released newly organized criminal evidence materials including the testimony and newly published personnel archives.

The Testimony

Tanizaki Hitoshi, originally named Ozaki Hitoshi, served as a medical orderly in the Hailar Branch of Unit 731 (Manchuria Unit 543). He joined the unit at age 21 in April 1944, and his testimony was collected during the Exhibition Hall’s evidence-gathering trip to Japan in 2016.

In his account, Tanizaki described his training and duties, including three months of initial training in preparing culture media in covered glass Petri dishes, applying bacterial strains, and incubating them until visible colonies formed. He also detailed his work managing wild rat breeding, recording birth and death counts, and frequently going into field trenches with a shovel to dig and catch wild rats.

Most critically, Tanizaki revealed the circumstances of Japan’s defeat. He confirmed that during the retreat, the Hailar Branch burned its facilities to destroy evidence, but the Japanese poison gas unit secretly buried large quantities of poison gas shells. “That was not bacteria, but poison gas,” he stated, adding that “the poison gas unit existed, established at the Fularji location.”

Researcher Jin Shicheng of the Exhibition Hall said the testimony directly confirms that Japanese forces abandoned chemical weapons in China at the time of defeat, explaining the historical roots of post-war poison gas hazards. “This oral testimony directly confirms that Japanese forces abandoned chemical weapons in China at the time of defeat, and also explains the historical roots of post-war poison gas hazards, which has practical significance,” Jin said, as reported by Guancha.

Personnel Archives Reveal Cover-Up Operations

On the same day, the Exhibition Hall also published the “Personnel Declaration” archives of the Hailar Branch, totaling 185 pages covering 156 members, according to China Military Online. The archives reveal that Japanese forces used the cover of regular infantry units—including Manchuria Unit 97, Unit 177, and Unit 201—to conceal their bacteriological warfare activities. Personnel were recruited under these cover names, trained for three months at Unit 731 headquarters, and then assigned to the Hailar Branch.

Of the 156 members listed in the archives, 145 were captured by Soviet forces after the war and detained in the Soviet Union, with four tried in Khabarovsk between April and September 1950. This confirms that Soviet investigation and judicial accountability for Japanese bacteriological warfare crimes continued after the 1949 public trial.

The Hailar Branch was one of five branches established by the Japanese Kwantung Army for Unit 731 in northeast China. Located in the northeastern part of Inner Mongolia near the China-Mongolia-Soviet border, it served as a frontline base for bacteriological warfare against the Soviet Union.

The Ongoing Chemical Weapons Crisis

The testimony comes at a critical time, as the issue of Japanese abandoned chemical weapons remains a serious and unresolved concern. Japan produced over 7,000 tons and 7 million poison gas shells between 1929 and 1945, with the vast majority transported to China. At the end of WWII, Japanese forces buried or abandoned these weapons rather than disposing of them properly.

In 1997, China and Japan signed the Memorandum on the Destruction of Japanese Abandoned Chemical Weapons in China. Under the Chemical Weapons Convention and the memorandum, Japan was obligated to complete destruction by 2007. However, the disposal plan has been delayed four times, and the process remains severely behind schedule.

The continued danger was highlighted on May 26, 2026, when two Japanese personnel were injured by chemical agents while handling abandoned chemical weapons in Jilin Province, as reported by Zao Bao. The two individuals were treated and returned to Japan on May 29.

On July 30, 2026, marking the 27th anniversary of the China-Japan memorandum, Chinese Foreign Ministry spokesperson Mao Ning addressed the issue directly. According to the Chinese Embassy in Colombia, Mao stated that “comprehensive destruction of abandoned chemical weapons is Japan’s unshirkable historical, political, and legal responsibility,” and strongly urged Japan to “provide effective burial site information as soon as possible, accelerate the disposal process, and thoroughly eliminate the hazards of abandoned chemical weapons.”

Historical Context: Unit 731’s Crimes

Unit 731 was a top-secret biological and chemical weapon research base established by the Japanese Imperial Army in 1932 in Harbin, northeast China. It conducted experiments on at least 3,000 people—including Chinese, Korean, Soviet, and Allied prisoners of war—while more than 300,000 people across China were killed by Japan’s biological weapons. The unit was led by Shiro Ishii and operated under the cover name “Epidemic Prevention and Water Purification Department.”

Curator Jin Chengmin, who has made over 30 trips to Japan over 27 years to collect evidence from former Unit 731 members, has gathered 423 hours of video testimony. As of 2025, only four verified former Unit 731 members were still alive, all over 90 years old. In a Global Times interview published in August 2025, Jin reflected on the urgency of his work: “Some call it a massacre, but I believe that’s not accurate. It was an unprecedented medical crime in human history at the cost of destroying humanity.”

The testimony from Tanizaki is particularly significant because it connects the bacteriological warfare operations of Unit 731 with the separate chemical weapons units, showing the full scope of Japan’s weapons of mass destruction program in China. It also provides direct perpetrator-side oral evidence about the burial of poison gas shells—rare given that most former Unit 731 members either refused to testify or died without revealing their experiences.

Implications and Forward Look

The disclosure strengthens the evidentiary basis for China’s demands that Japan accelerate the disposal of abandoned chemical weapons. It also adds to the historical record that challenges Japanese revisionist narratives about WWII, as the Japanese government has historically denied or downplayed Unit 731’s activities.

Recent related developments underscore the continuing relevance of this history. In July 2025, the Exhibition Hall released an 83-minute complete oral testimony of former Unit 731 member Kurumizawa Masakuni, who admitted to dissecting over 300 people. In August 2024, former Unit 731 youth squad member Shimizu Fusao visited the Unit 731 site in Harbin to apologize at the “Repentance and No-War Peace Monument.”

As the number of surviving former Unit 731 members dwindles rapidly, the testimony collected by the Exhibition Hall becomes increasingly valuable as a historical record. The disclosure of Tanizaki’s testimony and the Hailar Branch archives represents a significant addition to the evidence base, providing both oral and documentary proof of Japan’s wartime chemical and biological warfare operations in China. The question now is whether this evidence will translate into accelerated action on the long-delayed disposal of abandoned chemical weapons—a matter of urgent concern for the safety of Chinese civilians and the broader trajectory of China-Japan relations.