You can only really understand the devastation that hit Hiroshima by going there as i suggested a few weeks back. The A-Bomb Dome was one of the only remaining structures that survived, if only partially.
In the Hiroshima Peace Memorial Museum there’s a scale model of Hiroshima before and after.

Widespread destruction with only several buildings still standing.
A must visit for anyone getting down to Hiroshima, foreign or Japanese, is to the area the Atomic Bomb landed on August 6th 1945.
There’s many different areas to view different memorials and peace offerings but one exhibition was of special interest to me was the watch the now stands still, at 8:15 am, the time the Atomic Bomb devastated Hiroshima.

The watch is on display at the Hiroshima Peace Memorial Museum.
For my money, i can’t go past the Shinkansen for my means of long distance travel within Japan.
Not only is it a safer option, there’s much less stuffing around than with a plane, no security check, no carry-on luggage restrictions etc …
On my recent trip to Hiroshima and Kyoto i had the pleasure of riding the Shinkansen several times.

Although as a tourist there’s a JR Rail Pass you can get it’s not necessarily the best and easiest option.