Tsutomu Yamaguchi (山口 彊 Yamaguchi Tsutomu?) (16 March 1916 – 4 January 2010), was a Japanese national who survived both the Hiroshima and Nagasaki atomic bombings during the Second World War. Although more than one hundred people are known to have been affected by both bombings, he is the only man to have been officially recognised by the government of Japan as surviving both explosions.
A resident of Nagasaki, Yamaguchi was in Hiroshima on business for his employer Mitsubishi when the city was bombed on 6 August 1945. The following day he returned to Nagasaki and, despite his wounds, returned to work on 9 August, the day of the second atomic bombing. In 1957 he was recognized as a hibakusha (explosion-affected person) of the Nagasaki bombing, but it was not until 24 March 2009 that the government of Japan officially recognised his presence in Hiroshima three days earlier.