The two children in Grave of the Fireflies are fictional, but they're standing in for a tremendous number of real Japanese civilians killed by these events - in some cases literally starved to death. The Americans really did drop incendiary devices on those cities to burn homes to the ground, in our real world. You can certainly make an argument that it was somehow "justified" but it's a terrible thing to have done even if you're quite sure that it wasn't a war crime (which I am not).
FuriouslyAdrift
Grave of the Fireflies is "semi" auto-biographical
The two children in Grave of the Fireflies are fictional, but they're standing in for a tremendous number of real Japanese civilians killed by these events - in some cases literally starved to death. The Americans really did drop incendiary devices on those cities to burn homes to the ground, in our real world. You can certainly make an argument that it was somehow "justified" but it's a terrible thing to have done even if you're quite sure that it wasn't a war crime (which I am not).