https://www.youtube.com/watch?v=fpAgmvjJCtI
Wrong link, this is the one I meant to send you. Watch a minute or so and it’s exactly as you said. Like an alien invasion in their eyes. They were utterly unprepared mentally.
I remember watching “Barefoot Gen” about 25 years ago. A local UHF channel used to feature full-length anime movies late on Friday nights. (With good reason...a lot of anime definitely ain’t for kids!) I’d read plenty of accounts of the Hiroshima bomb, but seeing it depicted (even in anime) was something else entirely.
A detail that stood out to me in the English-language release was that, in the opening overlays, they identified how many cities were bombed, night after night after night, in the confined territory of the Home Islands...there was no avoiding the threat. The accounts in “Japan at War” really brought home what a shock it was to the interviewees.