‘The Sun had fallen to Earth’ — a survivor’s recollection of the Hiroshima bombing

By the summer of 1945, after peace was declared in Europe, Japan was the only power of the military coalition with Germany and Italy still at war. In Japan’s blockaded Home Islands, dwindling food supplies were prioritized for soldiers. Meanwhile, emperor Hirohito encouraged the country’s slowly starving civilians to gird for imminent invasion by Allied forces and to be prepared to give up their lives in the upcoming decisive battle that would determine Japan’s fate.

A five-month-long campaign of nightly US incendiary raids had reduced all but a handful of cities, in which most civilians lived, to cinders and rubble. One of the few urban areas to have escaped this storm of napalm and thermite was Hiroshima, a regional transport and manufacturing hub on the Seto Inland Sea.

Many of its 250,000 residents ascribed this run of luck to divine intervention by Buddhist or Shinto deities. But a pessimistic thread of gossip, shared in whispers and behind closed doors, posited — correctly, as it would turn out — that Hiroshima’s stay of incendiary execution was merely temporary, and in place only because the US government had something much worse in store for the city.

All hands on deck

Local authorities were not going to leave the city’s fate to chance. In late July, Hiroshima’s garrison ordered a massive municipal effort to clear areas for firebreaks in the central business district as a countermeasure to the sweeping fires that were expected once the US bombers finally got around to crossing the city off their rapidly dwindling target list.

In practice, this meant tearing down wooden houses and stores along designated thoroughfares and around key military and government buildings.

Providing the muscle on site were some 20,000 civilian volunteers. Most were farmers, men too old for military service and members of women’s patriotic associations. The adults were joined by Hiroshima’s cohort of 12- and 13-year-olds, born between 1 April 1932 and 31 March 1933.

During previous drives, children this young had been deemed too physically immature to join the city’s older schoolchildren, who, for nearly a year, had been toiling in area-munitions and aircraft plants, their education officially suspended. Now, however, the younger students represented a pool of workers too valuable to leave fallow any longer.

Although local school-board members and education officials had initially resisted putting their prepubescent charges in harm’s way, they eventually caved to army demands. On the morning of Monday 6 August 1945, commuters hurried into Hiroshima’s central business district along streets ringing with the high-pitched singing and call-and-response chanting of thousands of secondary-school students working on the firebreaks alongside their adult counterparts.

In the downtown district of Zakoba, some 300 first-grade students from the elite Hiroshima Prefectural Junior High were helping to clear wooden structures around city hall. That day, however, one boy was not on the job: 13-year-old Ōiwa Kōhei had woken up that morning with a stomach ache, and his mother agreed to let him stay at home.

Out of the blue

In the minutes before 8:15, observation posts in the prefecture’s eastern part began calling in reports to the regional air-defence headquarters bunker in Hiroshima Castle: two unidentified aircraft were approaching the city at high altitude. This seemed no cause for urgent alarm — B-29 aeroplanes had been flying over the city all summer, alone or in small formations, not dropping even a cigarette butt or an empty coke bottle on the way. Still, going by the standard civil-defence protocol, the intruders’ presence should have merited an air-raid warning to alert the populace and give people time to take cover — in a proper bomb shelter, or at least under a roof somewhere.

Indeed, one hour earlier, sirens had sounded when a single B-29 had flown a couple of lazy circuits high over Hiroshima, and people across the city — mainly women, children and older people — had remained hidden until the all-clear signal, 30 minutes later. This time, however, when reports about the second contact began to come in, the day’s air-defence duty officer — the only bunker staff member with the authority to activate the city’s air-raid sirens — was away from his desk, consulting with colleagues at headquarters. Hiroshima’s sirens remained silent, and its residents went about their business as they would on any Monday morning.

At 8:14, the inbound aircraft abruptly went into a dive, made a full-throttled U-turn and flew away at maximum speed. People on the ground — alerted by the growl of straining engines overhead — stopped what they were doing and looked up to see three white parachutes trailing one of the bombers. Thinking that these were US crew members bailing out of a stricken aircraft, many let out cheers.

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Few people, however, had noticed a long grey cylinder — dropped by the second plane — that had already been falling for half a minute or so by the time the sound of the steeply banking aircraft reached the ground.

During a free fall of 45 seconds, this sarcophagus-like object — called Little Boy by its US makers — plummeted some 9.5 kilometres before its onboard sensors detected an altitude of 600 metres, the designated air-burst height carefully calculated by scientists at the Los Alamos laboratory in New Mexico to maximize the effect of the blast. At this point, the two halves of Little Boy’s nuclear core slammed together to form a supercritical mass of 64 kilograms of the radioactive isotope uranium-235.

Although only one kilogram of the core underwent fission before the bomb exploded, the chain reaction that took place during this blink of an eye produced a kinetic-energy pulse equivalent to 15,000 tonnes of exploding TNT.

Total devastation

To witnesses on the ground, this release of energy was initially expressed as a blinding flash of light ‘brighter than a thousand Suns’. Some 0.2 seconds later, it became a fireball — a roiling, 300-metre-wide sphere of air superheated and hyper-pressurized into ionized plasma.

This fireball assailed the crowded wooden city below with two vectors of immediate destruction. The faster of these was a burst of radiation across the electromagnetic spectrum — γ rays, X-rays, ultraviolet light, visible light and thermal rays — that reached the city at the speed of light, baking every surface it touched to temperatures ranging from 3,000 to 4,000 °C for up to eight seconds. In a combustion zone with a radius of about 1.5 kilometres from Little Boy’s hypocentre, every bit of organic matter directly exposed to this heat (twice the melting point of steel) immediately burst into flames.

Contrary to post-war US narratives about the bombing, no one caught out in the open in the combustion zone was ‘instantly vaporized’ — not even someone hypothetically standing at the hypocentre, directly under the air burst. Instead, people were essentially burnt alive for several seconds until Little Boy’s briefly supersonic shock wave front — the bomb’s second vector of fast-acting destruction — ended their agony by blowing their rapidly carbonizing bodies to pieces.

This blast of hyper-compressed air smashed and flattened everything in the roughly 1.5-kilometre radius of total destruction. In the process, it also initiated a massive atmospheric displacement centred over the explosion’s hypocentre. After the dissipation of the shock-wave front, air from the surrounding area rushed back in to fill the temporary vacuum. This allowed thermal radiation from the still-burning fireball to promptly ignite central Hiroshima’s splintered wooden remains.

In short order, thousands of blazes merged into a fire storm so powerful that it created its own localized weather system and spread far into the parts of the city that had otherwise escaped Little Boy’s initial fury. This conflagration would rage for 24 hours and consume most of Hiroshima.

With the fireball’s brief existence having run its course and its incendiary mission accomplished, it was subsumed and sucked up and away into a skyrocketing, kilometres-high pillar of fire, smoke, dust and ash produced by the pyre of the dying city. Although this rising column of airborne debris had yet to reach its terminal altitude and flatten out into its iconic ‘mushroom cloud’ cap, tens of thousands of people already lay dead across Hiroshima, killed by the combined effects of the bomb’s electromagnetic burst and blast effect.

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Tens of thousands more would die across the city in the fire storm of 6 and 7 August. They perished in burning, crowd-crushed streets and alleys, or trapped under the wreckage of collapsed houses, or because they jumped into the city’s many waterways and drowned. By nightfall, 80,000 people had died, including almost the entirety of the firebreak work force.

In the subsequent days, weeks and months, tens of thousands of people (including first responders and carers) would die agonizing, effluvia-spewing deaths at the hands of a third, slower-acting vector of destruction: acute radiation syndrome. By the end of the year, 140,000 people had died from bomb-related causes, with another 74,000 dead in Nagasaki during the same period, because of a second atomic bomb, dropped on the city on 9 August.

Narrow escape

At the instant of Little Boy’s air burst, Ōiwa had seen a flash of light so bright that, for a few startled seconds, he thought that the Sun had fallen to Earth and landed in his mother’s flower beds. As his mind scrambled to process this thought, a whirlwind abruptly blew in all the windows in his house, lifted him from the tatami flooring and threw him across the living room and into the wall.

As was the case for everyone in Hiroshima’s destruction zone who lived to tell about it, the shock wave’s atmospheric displacement prevented Ōiwa from hearing Little Boy’s explosion. When air rushed back into his environment a few seconds later, the first thing he heard was his mother calling out to him from the kitchen.


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Owing to a fluke of topographical luck, Ōiwa’s home and much of the surrounding Danbara district had been spared the worst of Little Boy’s ferocity by a small but steep hill — Hijiyama — close to the neighbourhood’s western edge. After the explosion, while people on the other side of Hijiyama were dying or already dead, the Ōiwas and other Danbara residents had milled about outside, assessing the mostly minor damage to their homes and sharing theories about what had caused it.

But even as the western sky darkened with smoke — then turned orange with reflected firelight — they had no idea what was going on in the rest of the city until the first moaning survivors fleeing the burning city centre emerged from the untouched bamboo groves on the lee side of Hijiyama. Sitting or lying down on the ground after reaching their temporary sanctuary, many never got up again. By the afternoon, Ōiwa would be stacking their bodies with first responders — soldiers from an army kamikaze motorboat base in Hiroshima Bay.

Later recollections
Seven decades later, on a spring morning in 2018, 86-year-old Ōiwa is sitting across from me at the dining table in his comfortable western Tokyo home, showing the system of body retrieval he and one of the soldiers had used on the afternoon of the bombing. “Since the soldier was older and stronger than me, he would grab each body under the shoulders, while I would grab the ankles, like this,” Ōiwa explains, demonstrating with a two-handed grasping gesture.

While doing this work, 13-year-old Ōiwa had gradually slipped into a state of psychological shock — his brain’s last-ditch instinctive defence mechanism to preserve its host’s sanity — that nevertheless permitted his body to continue functioning with a sort of robotic efficiency. But even in this state of emotional numbing, there were still moments when the horror of his situation broke through. On several such occasions, when he bent down to grab yet another corpse, the burned flesh and heat-gelatinized cartilage of the corpse’s shins and ankles slipped off in his hands, like barbecued spare-rib meat falling from the bone. “If there is a hell,” Ōiwa recalls thinking at the time, “it must be just like this.”

For many months after the bombing, Ōiwa exhibited a litany of symptoms of acute radiation syndrome, including hair loss, bleeding gums and gastrointestinal distress. But the ravages the adolescent endured weren’t just physical — they were also psychological. One such manifestation was crushing survivor’s guilt; 73 years after the fact, he still winced noticeably as he recounted the shame he had felt at being the only child his age in his neighbourhood to have survived Little Boy’s wrath.

Moreover, for decades after the war, when radiation was still not well understood by the Japanese public, hibakusha (the Japanese term for atomic-bomb survivors) were often viewed by their fellow citizens with suspicion and even outward revulsion. Ōiwa was acutely aware of this pariah phenomenon — particularly after he moved to Tokyo in early adulthood — and he feared the social and professional ostracism that he was sure would follow if his Hiroshima past were to become known to his neighbours and co-workers. As such, he hid this identity from everyone but his wife — another Hiroshima survivor — until late middle age, when he joined a branch of the Japanese national hibakusha organization, Nihon Hidankyō, and began lecturing local school groups about his wartime experiences in his free time.

Compelling history
In May 2016, I was inspired by then-US president Barack Obama’s Hiroshima visit to undertake an oral history research project to record the testimonies of Hiroshima and Nagasaki survivors. It was my very good fortune that, early on in my project, I was able to secure the cooperation of Nihon Hidankyō in locating people willing to be interviewed for my research. Thanks mainly to this crucial cooperation, I was able to interview Ōiwa and 50 other Japanese, Chinese and Korean hibakusha over the subsequent three years.


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From the onset of my project, I sought to interview people who had been at least 12 years old at the time of the bombings. The idea was that the relative real-time maturity of such survivors would guarantee a reasonable degree of reliability in their narrative memories of the events of August 1945.

But limiting the scope of my study in this way meant that I also had to work against nature’s clock; participants were already in their eighties or older when I first approached them, and the handful who are still alive, and whose memories have not receded into the mists of cognitive senescence, are now in their nineties.

Since beginning my project, I have often found myself wondering what kind of a world the rest of us will inhabit when the last hibakusha has gone, taking with them their unprecedented lived experience and peerless moral authority to speak up about the horrors of nuclear weapons. No doubt the Nobel Committee members were entertaining the same train of thought when they decided to immortalize Nihon Hidankyō with the 2024 Nobel Peace Prize. Sadly, Ōiwa, who was at the time of our interviews the chair of the organization’s Greater Tokyo branch, did not live to witness this honour.

The hibakusha will not be with us for much longer, so it is essential that their irreplaceable living testimony should continue to be diligently and accurately recorded while it is still available. It has always been the expressed wish of Ōiwa and my other interviewees that the world will never witness the horror of nuclear warfare again. To this end, they wanted their testimony to be shared with the world, not only for the sake of historical posterity, but also in the hope — as the international community faces the prospect of another wave of nuclear proliferation — that current and future generations will take the lessons of the hibakusha’s experiences to heart.

Mordecai Sheftall

Nature.com