I asked Amritas, the master of linguistics that he is, about the origins of the word ”hibakusha”:

hi- = -ed (passive marker)
baku = explode (cf. genbaku ‘atom-explode’, short for genshi bakudan ‘atom bomb’ [bakudan ‘bomb’ < baku- 'explode' + dan 'projectile')
-sha = person

So it literally means something like 'the [atom-]bombed people'. And yes, it refers to survivors of Hiroshima and Nagasaki.

As I figured.
Most sci-fi novels I’ve read in my lifetime have referred to nukes as “the Fire” (capitalization deliberate). I most certainly don’t want to put the survivors of Hiroshima and Nagasaki down in any way, because they indeed hold a special place in our history...one which I pray will never be repeated.
When the Bombs went off, hundreds of thousands of people took their dying breath and into the atmosphere it went, and it got irradiated along the way. Like Caesar’s Dying Breath, we’ve breathed in those dying molecules.
My dad was in about three dozen tests back in 1958 when he was in the Navy. Think of those who assumed the “kiss your ass goodbye” position on the decks of the Navy ships at Eniwetok, or those who marched toward Ground Zero in Nevada...their legacy is with us now, as are those who were killed in Hiroshima and Nagasaki, who were the first.
Every day we live without using those nuclear weapons is a victory and we survive. Wouldn’t that make us all “survivors of the Fire?”

Just a thought.