Tsutomu Yamaguchi died on January 4 at the age of 93. I hadn’t heard of him before reading of his death, as I suspect you haven’t.
According to Wikipedia, he was on a business trip to Hiroshima, on August 6, 1945. As he stepped off a tram, an atomic bomb detonated three kilometres away. He was deafened, temporarily blinded, and half his upper body was burned. He spent the night in bandages in an air-raid shelter and returned home the following day.
Three days after the bomb, he was explaining to his boss how close he’d come to death when, three kilometres away, another atomic bomb detonated. His home was in Nagasaki.
According to the Washington Post article, “Double Atomic bomb survivor dies in Japan,” “Yamaguchi was the only person certified by the Japanese government as having been in both cities when they were attacked, although other dual survivors have also been identified.” I can find no information on why he alone received this certification despite more than a hundred others sharing a similar experience.
Yamaguchi suffered radiation-related health problems throughout his life and stomach cancer caused his death. He was a lifelong proponent of the banning of nuclear weapons.
Hat tip: Boing Boing