Great topic. I was thinking about this too.
A couple films I want to see are Children of Hiroshima (1952) and Black Rain (1989). Shindo is one of my favorites and Hiroshima was his hometown. I've never seen anything from Imamura so I'm interested to check him out.
And what about Nagasaki? Kinda overlooked. I know there was less damage, but they still got nuked.