Unit 731

Unit 731

April 02, 2025 36m Episode 6

Japan's infamous Unit 731 wasn’t just a research facility – it was a slaughterhouse where cruel human experiments blurred the line between science and sadism. And the cover-up almost worked...

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Binge all episodes of Don't Cross Cat early and ad-free on Wondery+. There's nothing wrong with the patient strapped to the operating table.
He's terrified and fighting against the restraints. But otherwise, this man is in perfect health until your supervisor steps forward and shoots him in the leg.
Remove the bullet you're instructed, so you obey. You've performed this procedure many times in school, but never on a patient like this, who's been given no anesthesia or painkillers whatsoever.
You work as carefully and compassionately as you can, but the patient screams and writhes the entire time. It's torture.
Once the bullet's out, you receive your next task.

Remove a piece of the patient's intestine. After that, a piece of his arm.
And after that, a chunk of his brain. You understand now, this patient is not meant to leave this operating table alive.
He's one of the truly unfortunate ones. He'll be kept conscious the entire time until scientific experiments become too much for his body to handle.
And once his body is wheeled off to the crematorium, another patient, another victim, will be brought in in his place. Again, you take up your scalpel and make the first decision.

You block out the patient's screams as well as your own conscience. This is no time to debate right from wrong.
You've already seen what happened to the other doctors who question orders in unit 731. one.
It's 1932. And deep in the heart of Japanese-occupied Manchuria, something monstrous is taking shape.
Near the city of Harbin, Chinese prisoners are being forced to construct a mysterious compound. It seems to be part army base, part laboratory.
But the prisoners don't know what they're building. Their Japanese oppressors make them wear blinders as they work, like horses, to keep them from grasping the full picture.
Because the horrifying truth is, many of these Chinese prisoners will never

leave this place alive. They're erecting a concentration camp for their very own extermination.

Overseeing the construction is an army medical officer named Shiro Ishii. Shiro is a man of

medicine, a man of ambition.

This facility is the culmination of everything he's worked for.

It'll be his personal playground, a place to perform unthinkable medical experiments on human beings with complete impunity.

Only he knows the horrors that are to come. Shiro has always believed that people deserve the lives they're born into.
As a child, this meant that the peasants working his wealthy family's land deserved the brutal mistreatment they received from Shiro's father. Poverty and suffering were simply their lot in life.
Shiro also believes he deserves the wealth and privilege he was raised in. The gods have smiled upon him.
He's destined for greatness. Shiro considers it his duty to socially climb.
And if lesser people get crushed under him along the way, well, then so be it. This attitude has served Shiro well.
By shrewdly placing himself near powerful people, he's received incredible medical research opportunities and has rapidly advanced up the ranks of the Japanese army. But the real reason he stands here today, overseeing the construction of a unique medical base catered to him, is because an idea occurred to Shiro.
An idea so horrific that few others would dare to even think it, let alone speak it out loud. But Shiro dared because he saw this idea as an opportunity to serve the most powerful person in all of Japan, Emperor Hirohito himself.
Just a few years prior, as a curious student of medicine and biological weaponry, the idea comes to Shiro while he's familiarizing himself with the Geneva Protocol. This agreement, signed by the League of Nations in 1925, bans the use of chemical and biological weapons in war.
Japan is emerging from a period of isolation, trying to learn from other nations and find advantages. But just because the Europeans decided to ban these weapons, doesn't mean Japan has to follow.
In fact, Shiro believes that the greatest men in the empire are those who can outthink those cocky westerners. One of his heroes is Togo Hayechiro, a Japanese admiral who achieved incredible military victories by ignoring many of the European rules of warfare.
Shiro wants to be just like him. Admiral Togo was a sailor who used innovative naval maneuvers.

Shiro's a doctor who will use biological weapons.

He thinks that they'll be of great use to the emperor.

After all, Japan doesn't have access to uranium like the great powers do.

But then again, they don't need uranium for biological weapons. Shiro believes this may even be why the West banned their use, because biological weapons could give lesser nations equal footing with the great powers.
The way Shiro sees it, if Western nations are so afraid of these weapons, then Japan should use them to make the West uneasy. And to realize his goal, Shiro just needs test subjects, humans specifically.
The only problem is, the Japanese government that Shiro serves won't experiment on its own people. Performing medical experiments on the precious subjects of his majesty is simply a bridge too far.
But as fate would have it,

Japan invades China in 1931, looking to take control of resources to fuel their growing empire.

Japanese high command might not be willing to experiment on their fellow countrymen,

but they'll have no problem experimenting on foreigners. In fact, they don't even see them as fully human.
So Shiro gets permission to carry out these human experiments in Manchuria, the eastern region of China that Japan has occupied. His base of operations, called Togo Unit after his hero, is established near the Manchurian city of Harbin, a mixing pot

of Chinese, Mongolian, and Russian cultures. It'll provide him with diverse test subjects

and plenty of them. But Shiro's experiments will soon go beyond the horrors of biological warfare

and into territory that is somehow much more disturbing.

In the fall of 1934,

one of Togo unit's Chinese prisoners, whom we'll call Li, has seen enough. For the past year,

he's witnessed firsthand the cruelty these Japanese invaders are capable of. They experiment on Li's countrymen as if they're lab rats, often killing their test subjects in the process.
But at this point, Lee no longer fears death. He's accepted that it arrives for all Togo unit prisoners eventually.
What concerns Lee more is how it'll arrive for him. Will he be fortunate enough to receive a quick and relatively painless death?

Or will he go like so many of the others,

screaming in agony from inside one of the compound's mysterious operation rooms?

It's autumn now, which makes Lee uneasy.

He knows all too well that the worst experiments come in the cold months. Lee will never forget last winter, when he and the other prisoners were given frostbite so the Japanese could learn how best to treat it and their own soldiers.
Sometimes they were taken outside and forced to dip their hands in cold water. They then had to wait for hours while their hands froze.
Others had to stand in the snow until their feet froze. And once they were thoroughly frostbitten, the prisoners were taken inside, where their frozen limbs were plunged into different buckets of water.
The Japanese tested different water temperatures,

finding out that 98 degrees Fahrenheit

was the optimal temperature for treating their affliction.

Sometimes the prisoners' limbs recovered.

Other times they were sawed off for further study.

Lee used to consider himself one of the lucky ones

because he survived.

But now, a year into his imprisonment,

he's no longer so sure. He used to love autumn.
But now, as Lee looks out through the bars of his cell at the colorful foliage outside, he sees the bright leaves for what they really are. Like Lee himself, the leaves are already dead.

He knows it's time to make a bold decision, because this may be the last opportunity he ever gets. The day of the local mid-autumn festival arrives, a time of celebration.
Lee watches the Japanese These guards drink one bottle of sake after another. The usual patrols of the cell blocks slowly fall off as more and more guards are pulled into the festivities, leaving the prisoners unattended.
The few guards left in the cell blocks are drunk and are falling asleep at their posts. As one guard after another slips into unconsciousness,

Lee calls out to the prisoners in his cell block. They need to act now.
He rallies them,

telling them it's now or never. If they're gonna die, let them die as men, not lab rats.
Lee's fellow prisoners agree to follow him.

He seizes a wine bottle from a nearby sleeping guard,

smashes him over the head with it, and steals his keys.

He opens every cell, telling the prisoners to get ready.

They're about to make a break for the wall.

Some of the prisoners have their feet shackled.

Lee didn't plan for this.

But there isn't time to find every key for every pair of cuffs.

The shackled prisoners will just have to try their best to keep up, even held back by their restraints. Moments later, the prisoners burst out into the night.
The cold autumn air whips at their faces. They creep behind several buildings, careful to avoid the areas some celebration.
Finally, they reach the wall and climb over a spot that the drunken guards have left unattended. Despite the cold, Lee is sweating profusely.
Heem hisses at his comrades, urging them to scale the wall as quickly as possible. Two, three, four, five.
Soon, most of the 16 prisoners are over the wall. And that's when they begin to hear shouting from nearby.
The Japanese guards have spotted them. Now, it's every man for himself.
As the guards swarm towards them, Lee scrambles up the wall and hurls himself over the top.

A moment later, his feet hit the ground outside,

and he and the others who managed to get out bolted straight for the tree line.

Lee shudders to think of what might happen when those he left behind are recaptured.

What will happen to him if he's recaptured? Lee and his comrades press through the woods, traveling mostly at night. They have nothing to cover their hands and feet, and they're severely weakened from the Japanese experiments.
Some of the less healthy escapees die of exposure before they finally stumble across a friendly Chinese village. Out of everyone, 12 of the 16 prisoners who attempted escape have survived.
Though Li is now free, he has difficulty moving on. At night, he's haunted by the faces of the

men who didn't survive, and by the screams of men who were taken into the operating rooms. And as much as he longs to enjoy his freedom, thoughts of revenge begin to consume him.
When he learns of the escape, Shiro Ishii is furious.

Until now, he's managed to keep Togo unit's activities secret from the Chinese populace. But now that 12 prisoners are loose in the wild, the cat is out of the bag.
He doles out harsh punishments to everyone involved, prisoners and guards alike, so as to ensure that no one ever escapes again.

But the tighter he squeezes, the more things begin to slip through his fingers. A few months later, something explodes.
The blast rocks the compound, and Shiro Ishii emerges onto the grounds to find a massive fire raging across several of the buildings and a huge hole blown in the fortress wall. He scrambles his men, fearing that this might be a full-on assault from the Chinese.
But as Shiro watches and waits, no enemy troops appear. Eventually, Shiro pinpoints the source of the explosion.
The guards' ammunition stores. Somehow, they were ignited.
This time, Shiro isn't sure where to aim his range. Is this more weakness, more incompetence from his men? Have they lost the stomach for their important work here? Or is the Chinese resistance responsible for this blast? He can't even allow himself to fathom the possibility that the prisoner Lee and some of the other rebels could have overcome his defenses and sabotaged his facility.
Shiro cannot and will not let it happen again.

His career and his service to the Japanese High Command are all that matter. He aims to prove to the world just how strong he is by constructing a new facility, one that'll be bigger, more secure, and carry out even worse atrocities in the name of science and his own morbid curiosity.
Shiro returns to Japan and uses his guile to seek funding for the new facility. Japan's high command is so impressed with Shiro's research results that they completely overlook the prisoner escape and explosion mishaps.
And rather than chastising Shiro, they grant him funding and promote him to Colonel. Shiro returns to Harbin with permission to construct a new facility that fully meets his needs.
He orders the old one demolished and has all of its prisoners executed. It seems only logical no one outside of the army can have knowledge of his work.
And there are always more test subjects to be found. He moves his operation a few miles away from their previous location to the Pingfan neighborhood of Harbin.
There, the Japanese army forcibly removes 600 families to make way. Shiro again uses Chinese prison labor to construct his base of operations, but this new compound is a much, much larger project.
It's hardly comparable to Togo unit at all. Stretching out over 800 acres, this new compound features 150 buildings, offices, civilian housing, farms, and even a power plant.
Everything it needs to be entirely self-sufficient. But that's all in service to his real goal.
The goal of performing human experiments. There are entire buildings devoted to surgeries and autopsies.
One even has refrigeration units to allow Shiro's men to conduct their frostbite experiments year-round. But buildings number 7 and 8, hidden secretly within an even larger one, are the most important.
Codenamed Ro and Ha, they house the male, female, and child prisoners. Shiro doesn't want any saboteurs attacking the new facility, so he keeps all of their activities confidential.
At night, he has prisoners brought in through an underground tunnel, tied up in bags and hidden in truck beds. While they're mostly Chinese, there are also Russians, European Jews, Mongolians, Koreans, and by 1939, even Allied soldiers.
The new prisoners are watched over by Shiro's own brother, the new prison warden. Having a family member oversee security ensures that the weakness his guards showed in the past will never trouble him again.
Effectively, Shiro has absolute authority over this complex. And here, he is a god.
The cover story for this complex is that it's not a prison, but a logging facility. And so, Shiro starts referring to his prisoners as Maruta, the Japanese word for logs.
With this, he makes sure all of his soldiers and scientists do the same. It's another step towards completely wiping away the humanity of these prisoners.
Something Shiro understands is absolutely crucial. He now oversees thousands of Japanese soldiers and medical personnel on the compound.
And if Shiro is to keep everyone in line, they must all view the prisoners the same way he does. All less than human.
Shiro won't repeat the same mistakes from Togo Unit. The past is water under the bridge.
Now there is only Unit 731. Shiro develops a routine, traveling back and forth from Japan and China to further his work.
As much as he relishes showing off for his superiors back home, his favorite times are always when he's back at the main Unit 731 complex, witnessing science in action. On one of his many routine inspections, he sits in as a young doctor performs his first practice surgery.
They do these a bit differently at Unit 731 than at the universities in the Motherland. Amused, Shiro watches to see how the young doctor reacts when he's told to perform surgeries on an otherwise healthy patient.
The young doctor hesitates, and Shiro despises that. But once Shiro steps forward, allowing his presence to be known to this new doctor, he notices a shift in the young man's eyes.
The doctor's confusion is replaced with understanding. Ignoring Shiro Ishii's orders would be a dangerous choice.
The young doctor complies and takes up his scalpel. Content, Shiro steps back into the shadows and watches the doctor perform a human vivisection, cutting into the screaming, thrashing Chinese patients on the operating table, removing pieces of organ and flesh.
However, when it's time to put the patient down, to throw the long into the fire, so to speak, the young doctor again hesitates. This does not impress Shiro, and so he marches forward, takes off his own belt, and wraps it around the patient's neck.
He looks the doctor in the eye as he squeezes the life from the patient

without a second thought. This is how it's done.
This is all these creatures deserve. Shiro ensures that the doctor is scheduled for several more practice sessions, and he reminds him that only traitors hesitate.
Shiro much prefers the work of the colleagues who have been with him for quite some time. He commends the perseverance of the doctors studying STDs.
They have to contend with difficult female prisoners who were wrongly inseminated by male prisoners at gunpoint. And once the women come to term, the doctors perform difficult surgeries on them.
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ship's ship's ship's ship's ship's ship's ship's ship's ship's ship's ship's ship's ship's ship's inseminated by male prisoners at gunpoint. And once the women come to term, the doctors perform difficult surgeries on them, operating on the women as they give birth to see how the infection has spread to the fetus and how trauma impacts it.
When Shiro observes these surgeries, he can't help but find it fascinating just how much pain his logs can endure.

Shiro is equally amazed by the creativity of his men.

As he walks through his 800-acre playground,

he witnesses an experiment where a log is hung upside down

to see how long it takes for it to choke to death.

In another building, he happens upon an experiment in where a log's right hand is sawed off and moved to his left arm to see if it still functions. And at the final stop of Shiro's inspection, he watches with pride as some of his men construct a giant centrifuge.
They strap logs to it and spin them around at extreme speeds to see just how much g-force a human can withstand before dying. Though Shiro is unashamed of the work being done at Unit 731, he knows that they can't be too transparent when publishing their results, at least not until Japan is able to bring the emperor's might to the rest of the world.
So when the unit publishes its research, they claim that they used not humans, but monkeys as test subjects. Internally, the prisoners are logs, a resource to be used.
And in the wider world, their animals sacrificed for the greater good.

But nowhere in this line of thinking, in Shiro's mind, are they ever considered human. Shiro is fascinated by Unit 731's discoveries relating to the limits of the human body.
However, Japanese High Command is less interested in how best to protect soldiers from frostbite and infection, and more interested in how to better kill the enemy. That was, after all, how Shiro sold them on the entire Unit 731 program.
And he hasn't been slacking on that front. One of the buildings at Unit 731 is entirely dedicated to rats.
In fact, the building houses over 3 million of them. The rodents are kept in special containment and are infected with fleas that themselves have been infected with a variety of deadly diseases.
The rats eventually die, but the fleas are resilient and are collected and loaded into ceramic bombs. This may have been an odd delivery method, but Shiro has his reasons.
Any kind of combustible shell will incinerate the fleas. He wants something lightweight and fragile.
The ceramic will shatter and the fleas will survive, spreading throughout enemy territory and infecting the population. The West might have uranium, but Japan has Shiro Ishii, and what Shiro understands is that there's more than one way to build a weapon of mass destruction.
He first tests his biological weapons in October of 1940, and by 1945, there are Unit 731 satellite facilities throughout China breeding their own infected fleas for deployment. The fleas are bloated into ceramic bombs, which crack open upon impact without incinerating the payload.
The fleas' infections are passed along to Chinese villagers in the area who develop terrible, debilitating fevers. Essentially, they have contracted the plague.
Yet it doesn't end there. They notice strange yellow blisters on their bodies.
These blisters ooze yellow pus. Their bodies are rotting.
They have been infected with anthrax. Shiro didn't just drop the bombs with fleas.
Rather, he dropped a variety of them that infected both the land and water with everything from anthrax to typhoid. Not knowing this, the villagers do their best to improve sanitation.
Raths are killed on sight. When a villager succumbs to the illness, their bodies quickly buried outside of town.
But of course, it's not enough. Once the villagers get desperate, Shiro sends his men in.
They set up triage centers, pretending as though they want to aid the infected populace. But once the villagers enter these triage tents, they never come out.
Shiro's men learn what they can from the infected by dissecting the villagers alive. They don't bother using anesthesia.
Shiro's biological weapon attacks will kill 300,000 Chinese civilians over the duration of this war. But Shiro's obsession with biological weapons and his blind loyalty to the emperor comes with a price.
World War II is about to take a sudden turn for the unexpected, placing Japan and Shiro in a precarious position. For the first time in years,

Shiro has to stop thinking about how to kill others

and for once,

start worrying about how to keep himself alive.

On August 9th, 1945,

Shiro Ishii receives orders from his superiors.

Destroy all evidence of Unit 731. He wastes no time in complying.
He has all prisoners immediately removed from their cells and cremated. It's as horrific an act as any Shiro has ever committed.
Shiro sets about destroying the very compound he worked his entire life to build. He instructs his men to place dynamite throughout the main Unit 731 complex to reduce it to rubble.
They, of course, obey his orders. Shiro orders some of his men at the satellite facilities near the Russian border to do the same, and issues them potassium cyanide pills in case they're captured by the Soviets.
Shiro, however, does not go down with the ship. Even after the deaths of so many prisoners, so many Chinese civilians, so many of his own subordinates, he still feels no guilt and takes zero responsibility.
As always, this man is only focused on himself. And so, he attempts to fake his own death, spreading word that he was killed by the enemy.
Japan surrenders to the Americans in September of 1945, and soon, American forces are sweeping both Japan and China to learn what they can about their defeated enemy's operations. General Douglas MacArthur, responsible for the Pacific Theater, eventually discovers Shiro's lab in Tokyo and the ruins of his facility in Harbin.
But when American officials interrogate Japanese high command, they're repeatedly told that the Japanese authorities had zero knowledge of any biological warfare programs. Rather, they blame everything on Shiro Ishii.
It seems that Shiro was far too infamous and left too much of a trail for the Americans to follow, because in January 1946, America locates him. But Shiro's always been good at sucking up to his superiors, and that's not gonna stop now.
Even if they betrayed him to the Americans, Shiro is still deluded enough to have loyalty to the ruling class he was born into. It's acceptable for a commanding officer to throw an inferior under the bus,

but that same inferior should continue to protect higher-ups.

If nothing else, Shiro knows that sticking to this cone means he'll be rewarded

when he comes out the other side of this ordeal, if he can play his cards right.

Shiro has always been a complex man.

His morbid curiosity, his lack of empathy, got him this far. But now, his instincts for self-preservation kick in.
Shiro knows that the Americans know what he's been up to. Unit 731 was already the world's worst-kept secret.
Their research was too widely published and too well reviewed for his blatant lie to still hold up. Students in Tokyo have been shown graphic

photography of his vivisections as part of their curriculum. In essence, he's famous.

And now, MacArthur's men have had months to comb through the ruins,

interrogate witnesses, and learn more about what Shiro was really up to. And all that's left to Shiro is survival.
When he's interrogated, Shiro informs the Americans that he will talk under one condition. That General MacArthur grant him and the other Unit 731 staff full immunity.
Shiro has destroyed all of the evidence, but he and his men have detailed memories of their research. They shared some things with the public through their research papers.
But the most important data, how their weapons performed in the field, that is what the Americans want. And that information exists only in the minds of Shiro and his underlings.
The U.S. State Department is horrified at the proposition.
For the past year, they've been prosecuting Nazis for war crimes. And by comparison, Shiro puts even their atrocities to shame.
But MacArthur, and by extension, President Eisenhower, feel that the research is too valuable. As horrific as Unit 731's experiments were, they did provide insights into pathology that the Americans can put to use in their upcoming Cold War against the Soviets.
Shiro's offer is accepted. He and his men go free, and their research is labeled top secret, meaning that it can't be used as evidence of war crime.
On top of this, Shiro maintains his lie that Japanese high command knew nothing about his research. He goes to great lengths to protect them and the emperor.
In the end, there were thousands of soldiers and doctors in Unit 731, and yet only 12 are ever punished when the Soviets capture them and put them on trial. The U.S.
government doesn't even change its mind in the 1970s when it comes to light that hundreds of American POWs were experimented on like lab rats by Unit 731. Shiro and his men are never held accountable.
They go about their lives. They reintegrate into society.
They go on to occupy some of the highest positions at Japanese medical schools, pharmaceutical companies, and even Japan's medical association. Perhaps this is the scariest thing of all, because whether they knew it at the time or not, every single Japanese soldier and doctor at Unit 731 contributed, at some level, to the unspeakable evil that took place there.
But they weren't all psychopaths like Shiro Ishii. Many were average people, manipulated into following orders.
These people were told it was for their country and their emperor. They were told it was

okay because Japan is superior. Unit 731 is proof that it only takes a few monsters to turn an

entire group into a terrifying horde. And with that being the case, the chilling question we're

left with is, could Unit 731 ever happen again? is created and hosted by me, Nexpo. I love you all, and good night.
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