Yamaguchi, the first person to be confirmed as a double atomic bombing survivor, had been battling stomach cancer. A private funeral attended by his close relatives has been held.
A design engineer at the Mitsubishi Heavy Industries Nagasaki Shipyard during World War II, on Aug. 6, 1945 Yamaguchi was in Hiroshima on business just three kilometers from ground zero when the bomb went off. He returned to Nagasaki by train on Aug. 8, and was once more three kilometers from the nuclear detonation that destroyed the city the following day. Yamaguchi lost his hearing in his left ear in the blasts, and was afflicted with acute leukemia, cataracts and other bomb-related illnesses in subsequent years.
Aiming to communicate his thoughts on nuclear disarmament and peace, Yamaguchi self-published a volume of tanka poetry entitled "Ningen Ikada" in 2002. He began serious efforts to share his nuclear bombing experiences in 2005, after his son -- six months old at the time of the Nagasaki bombing -- died at the age of 59. In August 2006, he visited the United Nations in New York to show a documentary film he appeared in and appeal for the abolition of nuclear weapons.
In December last year, Yamaguchi also met with "Avatar" director James Cameron to discuss a possible film about nuclear arms, saying, "I think it's (Cameron's) destiny to make a film (about nuclear weapons)."
Yamaguchi was officially recognized as a double bombing victim in March 2009.
In 2005, the Hiroshima National Peace Memorial Hall for the Atomic Bomb Victims conducted a study of some 100,000 first person accounts of the bombings and the records of some 17,000 of the dead and found nine individuals who were victims of both the Hiroshima and Nagasaki bombs. None of the nine have been officially recognized.