In Nagasaki we visited the Atomic Bomb Museum and we all felt that the displays were much more graphic than those in Hiroshima. If you want to get a first-hand account of the day the bomb was dropped and its aftermath, you should read The Bells of Nagasaki by Takashi Nagai, a doctor who cared for the sick and dying while he was sick himself. It's very moving. Also (on a lighter note) the doctor advocated using sake for medicinal purposes:
"Rice wine, or sake, proved to be an excellent medicine. There were examples of dying persons being cured at the last moment by drinking a large quantity of their favorite sake."
Nagasaki is a sister city of St. Paul's and we were charmed to find a St. Paul Street and even a St. Paul parking garage!