Veterans have revealed some of the awful and heartbreaking experiments Japan’s scientists conducted on prisoners and civilians.

Most are aware of the horrors of Germany’s crimes during World War 2, however, the barbaric human experiments held by Japan’s scientists are often forgotten or overlooked.

Over the years, some veterans have come out and spoken about what they witnessed and what they participated in.

Some of the most gruesome experiments and tests at Japan’s secret biological warfare facility - named Unit 731 - are almost too awful to imagine.

The covert operation was run originally under the guise of a lumber mill, then a water purification plant.

Speaking on his own actions during the war back in 2006, an 84-year-old man named Akira Makino said that he had performed surgery and amputations on multiple prisoners of war while they were still alive with no anesthetic.

This was before they were executed via hanging to prevent them ever speaking out what they had suffered through.

Several veterans have admitted conducting human vivisection - surgery conducted for experimental purposes on a living organisms - in northern China as part of Japan's wartime chemical and biological weapons program.

Mr Makino said that as a 22-year-old he had operated on about 30 prisoners between December 1944 and February 1945 while working as a medic on the island of Mindanao.

It is believed more than 3,000 people, mostly Chinese civilians, but also Russian, British and American prisoners of war were dissected, tortured or infected with diseases like the plague and experimented on.

As well as amputations, he was ordered to conduct abdominal dissections and other experiments on condemned men, women and children.

Speaking to Kyodo news he said: "I thought, 'What a horrible thing I am doing to innocent people, even though I had been ordered to do it."

Mr Makino said he was too scared to refuse.

"I would have been killed if I had disobeyed the order," he said. "That's how it was in those days."

More recently, in 2023, Hideo Shimizu, a 93-year-old who was just 14 he was drafted as a cadet to the city of Harbin, spoke of his own experiences at the facility.

“I knew nothing about what the army was or what it did specifically,” he said in a recent interview.

He explained that he was taken to a specimen room in the facility, and he saw severed human body parts preserved in formalin.

"There were ones that had been sliced in two vertically, so you could see their organs," Shimizu said.

"There were children; ten or twenty of them, perhaps more. I was dumbfounded. I thought, 'how could they do this to a small child?'"

Shimizu was saved from having to participate as the war ended abruptly weeks later with Japan's surrender.