A hefty book containing some 750 letters from Japanese students expressing gratitude for support they received from the United States after the 1923 Great Kanto Earthquake has been preserved by a descendant of then-U.S. President Calvin Coolidge, a Japanese research team has learned.

Researchers from Tohoku University and other institutions were shown the letters, written in English by students from disaster-affected areas and elsewhere in Japan. With the discovery coinciding with the centenary anniversary of the disaster, they are now calling on the public for help in understanding how the letters came to be sent.

According to this year's White Paper on Disaster Management by the Cabinet Office, of the roughly 30 nations that sent donations to Japan in the aftermath of the Kanto quake, the United States was by far the largest contributor.