A former member of Japan’s notorious Unit 731 has publicly confessed to witnessing horrific human experimentation during World War II, including the dissection of pregnant women for research. The revelations, coming nearly 80 years after the war’s end, offer a chilling glimpse into the brutality of the unit’s operations and underscore the lasting trauma inflicted by Japan’s wartime actions in China.
95-year-traditional Shimizu Yasuo recounted his experiences in a December 2025 interview with the Japanese media outlet Shueisha, describing a profound and enduring regret for the actions he witnessed. “It wasn’t something humans should do…,” he stated, adding that he continues to experience nightmares related to his time with the unit.
Shimizu was recruited by the Japanese military in March 1945, at the age of 14, and assigned to Unit 731 as a trainee technician. Along with approximately 40 other teenagers, he was transported to a large facility near Harbin, in Japan’s puppet state of Manchukuo, following a period of basic military training. He and three others were then assigned to a “training department laboratory” where they conducted experiments related to bacterial cultures, under strict orders to maintain secrecy about their work.
Following his training, Shimizu was taken alone to the unit’s specimen room. There, he saw human organs preserved in formaldehyde, each labeled with the ethnicity and age of the donor – including markings identifying them as “Chinese” or “Russian.” He also described seeing the dissected bodies of pregnant women, with their abdomens open to reveal the developing fetuses. Some specimens were complete, while others consisted only of the torso, documenting fetal development at various stages of gestation.
“Honestly, I couldn’t bear it,” Shimizu said, recalling the sight of the specimens.
Unit 731 referred to those subjected to experimentation as “Maruta,” a dehumanizing term. Shimizu initially believed these individuals were war criminals, but witnessing the specimens firsthand, he found the acts to be unbearably cruel, though he felt powerless to escape. He continued to work in the laboratory, battling a growing sense of resistance.
The revelations come as historical scrutiny of Unit 731 continues to grow, with ongoing efforts to document the full extent of its atrocities. The confessions of Shimizu and other former members provide crucial firsthand accounts of the unit’s horrific practices.
Another former member, Kazuo Hu, also recalled witnessing similar scenes during an interview with China’s CCTV News, according to reports. The details of these experiments highlight the systematic and brutal nature of the unit’s operations. The accounts serve as a stark reminder of the human cost of war and the importance of confronting historical injustices.
