One glance at the run-down block in central Tokyo's Bunkyo Ward may suggest nothing but derelict industry, easily passed by, but in reality it is where Japan engaged in its own abortive version of the Manhattan Project.

The nondescript buildings belie this little known history and the feverish race toward the end of the war by an embattled Japan to produce what was hoped would be a "decisive weapon" — an atomic bomb.

It was here at the former site of Rikagaku-kenkyujo, or Riken, the Institute of Physical and Chemical Research, that the nation's top scientists under the direction of Yoshio Nishina faced increasing pressure from the government and military to make a nuclear bomb for use against the United States.