Most Americans are unaware that during World War II Japan had two programs seeking to build an atomic bomb.
In 1939 Dr. Yoshio Nishina, a Japanese nuclear physicist, recognized the potential of the then theoretical atomic bomb. ( In 1934 Professor Hikosaka Tadayoshi theorized about such a bomb.) In 1940 he spoke with Lieutenant-General Takeo Yasuda, director of the Army Aeronautical Department’s Technical Research Institute, about the potential of an atomic bomb. The Japanese Army began its program to develop an atomic bomb in April 1941.
Meantime, the Japanese Navy began its own program creating the Committee on Research in the Application of Nuclear Physics chaired by Dr. Nishina in 1942. The Navy’s project ended in 1943 when the Committee reported that while such a bomb was feasible it predicted that it would be difficult for even the United States, with all its resources, to harness the power of the Atom in time to have an impact on the War.
However, the Navy dropping out had no effect on the Army’s program which continued on to the end of the War, hampered both by lack of materials and by ever heavier US bombing. How far the Japanese got is open to speculation as the project was veiled in the deepest secrecy during the War, and most documents pertaining to it were destroyed by the Japanese prior to the Surrender.
There have been persistent rumors since World War II that the Japanese tested a nuclear device prior to the end of the War, either on an uninhabited island off what is now North Korea, or near Konan in what is now North Korea on August 12, 1945. The documentation is currently lacking to substantiate those claims. What is certain however, is that the Japanese had an ongoing atomic bomb project at the end of the War. Given enough time, I think it is foolhardy to think that one of the more inventive nations on Earth would not have found their way around road blocks and managed to have constructed an atomic bomb. The development of the atomic bomb during World War II was indeed a race, and not just against the Germans.