The grandson of former US president Harry Truman, who authorised the atomic bombing of Japan during World War II, visited Hiroshima on Saturday before the 67th anniversary of its devastation.
Clifton Truman Daniel, 55, toured the Hiroshima Peace Memorial Park and offered a silent prayer for victims of the 1945 wartime nuclear bombing, press reports said.
He was the first Truman relative to attend the anniversaries of the bombings of Hiroshima on August 6 and Nagasaki three days later.
After visiting the Hiroshima Peace Memorial Museum, the former US president's eldest grandson told reporters he was struck most by the "message of peace the entire city is devoted to," according to Kyodo news agency.
Tens of thousands of people attend services every year to remember the more than 200,000 people estimated to have died in the bombings, either instantly or later from burns and radiation sickness.