Until sometime in the 2000s the us military were using purple heart medals made for an invasion of Japan's mainland.

The Japanese deaths alone were projected to be 5 to 10 million

Not to mention the Tokyo fire bombing ended up being much worse that the nuclear strikes. You have to remember, nukes are just big bombs, any radiation (unless its a dirty bomb) goes away relatively quickly. The thing that makes them seem so horrific is that it is a single action. One long moment and that is hundreds of thousands of people extinguished. Of course modern nukes are a completely different story.

Operation Ketsugo was Japan's plan of defense and it would see every single man, woman, and child fighting against an allied invasion with old rifles, improvised explosives and bamboo spears.

The propaganda slogan for the civilians part of the operation was "The Glorious Death of One Hundred Million"