In August of 1945, as World War II was nearing its end, the United States dropped atomic bombs on the cities of Hiroshima and Nagasaki three days apart, killing at least 100,000 souls. Tsutomu Yamaguchi survived both devastating blasts.

Yamaguchi was preparing to leave Hiroshima when the first atomic bomb fell. The 29-year-old naval engineer was on a three-month-long business trip for his employer, Mitsubishi Heavy Industries, and August 6, 1945, was supposed to be his last day in the city. He and his colleagues had spent the summer working long hours on the design for a new oil tanker, and he was looking forward to finally returning home to his wife, Hisako, and their infant son, Katsutoshi.

Around 8:15 that morning, Yamaguchi was walking to Mitsubishi’s shipyard a final time when he heard the drone of an aircraft overhead. Looking skyward, he saw an American B-29 bomber soar over the city and drop a small object connected to a parachute. Suddenly, the sky erupted in a blaze of light, which Yamaguchi later described as resembling the “the lightning of a huge magnesium flare.” He had just enough time to dive into a ditch before an ear-splitting boom rang out. The shock wave that accompanied it sucked Yamaguchi from the ground, spun him in the air like a tornado and sent him hurtling into a nearby potato patch. He’d been less than two miles from ground zero.

“I didn’t know what had happened,” he later told the British newspaper The Times. “I think I fainted for a while. When I opened my eyes, everything was dark, and I couldn’t see much. It was like the start of a film at the cinema before the picture has begun when the blank frames are just flashing up without any sound.” The atomic blast had kicked up enough dust and debris to nearly blot out the morning sun. Yamaguchi was surrounded by torrents of falling ash, and he could see a mushroom cloud of fire rising in the sky over Hiroshima. His face and forearms had been badly burned, and both his eardrums were ruptured.

Yamaguchi wandered in a daze toward what remained of the Mitsubishi shipyard. There, he found his coworkers Akira Iwanaga and Kuniyoshi Sato, both of whom had survived the blast. After spending a restless night in an air raid shelter, the men awoke on August 7 and made their way toward the train station, which they had heard was somehow still operating.

The journey took them through a nightmarish landscape of still-flickering fires, shattered buildings and charred and melted corpses lining the streets. Many of the city’s bridges had been turned into twisted wreckage, and at one river crossing, Yamaguchi was forced to swim through a layer of floating dead bodies. Upon reaching the station, he boarded a train full of burned and bewildered passengers and settled in for the overnight ride to his hometown of Nagasaki.

While Yamaguchi returned to his wife and child, the whole world turned its attention toward Hiroshima. Sixteen hours after the explosion, President Harry Truman gave a speech that revealed the existence of the atom bomb for the first time. “It is a harnessing of the basic power of the universe,” he said. “The force from which the sun draws its power has been loosed against those who brought war to the Far East.”

A B-29 bomber called the “Enola Gay” had taken off from the Pacific island of Tinian and flown some 1,500 miles before detonating a bomb known as “Little Boy” in the skies over Hiroshima. The blast had immediately killed some 80,000 people, and tens of thousands more would perish in the weeks that followed. Truman warned in his statement that if Japan did not surrender, it could expect “a rain of ruin from the air, the like of which has never been seen on this earth.”

Yamaguchi arrived in Nagasaki early in the morning on August 8 and limped to the hospital. The doctor who treated him was a former school classmate, but the blackened burns on Yamaguchi’s hands and face were so severe the man didn’t recognize him at first. Neither did his family. When he returned home afterward, feverish and swaddled in bandages, his mother accused him of being a ghost.

Despite being on the verge of collapse, Yamaguchi dragged himself out of bed on the morning of August 9 and reported for work at Mitsubishi’s Nagasaki office. Around 11 a.m., he found himself in a meeting with a company director who demanded a full report on Hiroshima. The engineer recounted the scattered events of August 6—the blinding light, the deafening boom—but his superior accused him of being mad. How could a single bomb destroy an entire city?

Yamaguchi was trying to explain himself when the landscape outside suddenly exploded with another iridescent white flash. Yamaguchi dropped to the ground just seconds before the shock wave shattered the office windows and sent broken glass and debris careening through the room. “I thought the mushroom cloud had followed me from Hiroshima,” he later told the newspaper The Independent.

The atom bomb that hit Nagasaki was even more powerful than the one dropped on Hiroshima, but as Yamaguchi would later learn, the city’s hilly landscape and a reinforced stairwell had combined to muffle the blast inside the office. His bandages were blown off, and he was hit by yet another surge of cancer-causing radiation, but he emerged relatively unhurt. For the second time in three days, he’d had the misfortune of being within two miles of a nuclear explosion. For the second time, he’d been fortunate enough to survive.

After fleeing from the skeleton of the Mitsubishi building, Yamaguchi rushed through a bomb-ravaged Nagasaki to check on his wife and son. He feared the worst when he saw a section of his house had been reduced to rubble, but he soon found both had sustained only superficial injuries. His wife had been out looking for burn ointment for her husband, and when the explosion came, she and the baby had taken refuge in a tunnel. It was yet another strange twist of fate. If Yamaguchi hadn’t been hurt at Hiroshima, his family might have been killed at Nagasaki.

In the days that followed, Yamaguchi’s double dose of radiation took its toll. His hair fell out, the wounds on his arms turned gangrenous, and he began vomiting incessantly. He was still languishing in a bomb shelter with his family on August 15, when Japan’s Emperor Hirohito announced the country’s surrender in a radio broadcast. “I had no feeling about it,” Yamaguchi later told The Times. “I was neither sorry nor glad. I was seriously ill with a fever, eating almost nothing, hardly even drinking. I thought that I was about to cross to the other side.”

Yet unlike so many victims of radiation exposure, Yamaguchi slowly recovered and went on to live a relatively normal life. He served as a translator for the U.S. armed forces during their occupation of Japan, and later taught school before resuming his engineering career at Mitsubishi. He and his wife even had two more children in the 1950s, both of them girls. Yamaguchi dealt with the horrific memories of Hiroshima and Nagasaki by writing poetry, but he avoided discussing his experiences publicly until the 2000s, when he released a memoir and became part of the anti-atomic weapons movement. He later journeyed to New York in 2006 and spoke about nuclear disarmament before the United Nations. “Having experienced atomic bombings twice and survived, it is my destiny to talk about it,” he said in his speech.

Tsutomu Yamaguchi wasn’t the only person to endure two atomic blasts. His coworkers Akira Iwanaga and Kuniyoshi Sato were also in Nagasaki when the second bomb fell, as was Shigeyoshi Morimoto, a kite maker who had miraculously survived Hiroshima despite being only a half-mile from ground zero. All told, some 165 people may have experienced both attacks, yet Yamaguchi was the only person officially recognized by the Japanese government as a “nijyuu hibakusha,” or “twice-bombed person.” He finally won the distinction in 2009, only a year before he died at the age of 93.