Five College Center for East Asian Studies Study Tours Website
"Visitors to Peace Memorial Park see brightly colored paper cranes everywhere. These paper cranes come originally from the ancient Japanese tradition of origami or paper folding, but today they are known as a symbol of peace. They are folded as a wish for peace in many countries around the world. This connection between paper cranes and peace can be traced back to a young girl named Sadako Sasaki, who died of leukemia ten years after the atomic bombing.
Sadako was two years old when she was exposed to the A-bomb. She had no apparent injuries and grew into a strong and healthy girl. However, nine years later in the fall when she was in the sixth grade of elementary school (1954), she suddenly developed signs of an illness. In February the following year she was diagnosed with leukemia and was admitted to the Hiroshima Red Cross Hospital. Believing that folding paper cranes would help her recover, she kept folding them to the end, but on October 25, 1955, after an eight-month struggle with the disease, she passed away.
Sadako's death triggered a campaign to build a monument to pray for world peace and the peaceful repose of the many children killed by the atomic bomb. The Children's Peace Monument that stands in Peace Park was built with funds donated from all over Japan. Later, this story spread to the world, and now, approximately 10 million cranes are offered each year before the Children's Peace Monument." (Hiroshima City Website)