An ancient Japanese legend promises that anyone who folds a thousand origami cranes will be granted a wish by a crane, such as long life or recovery from illness or injury. The crane in Japan is one of the mystical or holy beasts (others include the dragon and tortoise), and is said to live for a thousand years.
The Thousand Origami Cranes has become a symbol of world peace through the story of Sadako Sasaki, a Japanese girl who contracted leukemia as a result of radiation from the atomic bombing of Hiroshima during World War II. Her story is told in the the book "Sadako and the Thousand Paper Cranes".
Several temples, including some in Tokyo and Hiroshima, have eternal flames for World Peace. At these temples, school groups or individuals often donate Senbazuru to add to the prayer for peace. The cranes are left exposed to the elements, slowly dissolving and becoming tattered as the wish is released. In this way they are related to the prayer flags of India and Tibet.