The image of Obama’s arms wrapped around ​a tearful Mori at the Hiroshima Peace ​Memorial Park became a defining moment of that ⁠visit - the first ever by a sitting ​US president.

Mori was eight years old when the ​US dropped the atomic bomb on Hiroshima, flattening the city on August 6, 1945 and knocking him unconscious with the ​force of its blast.

Thirty years later, Mori ​embarked on a multi-decade quest to find victims who were ‌cremated ⁠at his school playground. His work also identified 12 Americans who died in the bombing.

He died in a hospital in Hiroshima on March 14, Jiji ​reported.

Many nuclear ​bomb survivors - ⁠known as “hibakusha” in Japanese - despite their advanced age and dwindling numbers, have ​tried to keep alive the legacies of ​Hiroshima ⁠and Nagasaki, the only two cities to ever suffer a nuclear attack.

The cities have counted some ⁠550,000 ​deaths from the attacks to ​date, including from illnesses related to acute radiation exposure.