Ryōkichi Sagane (嵯峨根 遼吉, 27 November 1905 – 16 April 1969) was a Japanese nuclear physicist who played a prominent role in the development of nuclear power generation in Japan. In 1945 he was the recipient of a letter written by American physicists working on the Manhattan Project, which was dropped over Japan during the atomic bombing of Nagasaki.
Source: “Ryōkichi Sagane”, English Wikipedia (CC BY-SA 4.0), excerpt