Masa Takeuchi and his involvement in the Japanese nuclear weapons research programme

There were two nuclear weapons projects in Japan during World War II: an army programme called ‘Ni-go Research’ and a much smaller ‘F-Research’ of the navy.1‘Ni-go Research’ was directed by Yoshio Nishina, a leading nuclear physicist at the Riken, the Institute of Physical and Chemical Research. The experimental physicist Masa Takeuchi (1911-2001), a member of Nishina’s nuclear research group, became one of the key fi gures of the army project. This paper will take Takeuchi’s case as an example of Japanese scientists involved in wartime research during World War II. His case illustrates how Nishina’s nuclear group adapted for survival to an extraordinary research environment in wartime.