Then you know full well and indeed mention that the military government was at odds with other factions in the government that never wanted the war to begin with. As the failure of the war became more apparent, the military faction was losing power. For God's sakes, they were people - some of them bought into the never surrender mentality but a lot of them knew better. Anyone who has even a casual knowledge of Japanese history will know that their most fanatic of traditions were upheld inconsistently at best. The surrender was going to happen, and we knew that - the bomb was purely to get a lead on the Cold War, not to end the Second World War.
And with all due respect to your grandparents - with ALL the respect due to them, sincerely - they signed up to risk their lives and the citizens of Hiroshima and Nagasaki didn't. I *know* how that sounds to you, but the casualties of war should be the warriors and not the civilians. I know you don't like to hear that, and hell, I'll even go one further - the casualties of war should be volunteer warriors not conscript warriors, but they definitely shouldn't have been civilians who were so close to surviving a war they had nothing to do with.