I would imagine most of the Manhattan Project isn't something ever taught or discussed among the Japanese. It's really only high in US curriculum because the project actually absorb an absolutely massive amount of resources. Plus, almost everyone involved became semi science celebs in the aftermath. However, I highly doubt almost anyone in Japan has heard of the Hanford Site or knows much about Los Alamos or Oakridge. Frankly, I'd be surprised if 10% of the Japanese could find New Mexico on a map. While a world changing event, the details are very much either an American or Science Nerd set of information, and one should probably not expect others to have my knowledge of it.
For the Japanese, also, Great Uncle Yuto might have been under one of them. Different perspectives.