On August 9, 1945, an atomic bomb was dropped by the Americans over Nagasaki, killing tens of thousands of people in an instant and leaving behind immense devastation. Among the survivors was Takashi Nagai, a pioneer in the field of radiology. Nagai grew up in a Japanese family that practiced Shintoism. In addition to the intriguing details of Japanese culture and history, the author recounts Nagai's childhood and his studies in medicine in Nagasaki. He experienced the occupation of Manchuria as a soldier in the medical service. His spiritual journey from Shintoism to atheism and ultimately to Catholicism is remarkable. He eventually married Midori, a deeply devout Christian. When the atomic bomb was dropped, Nagai lost his beloved wife. His grandmother survived with the two children because he had sent them to relatives in the countryside.