Okay kiddo, do you know what war is? It's when countries fight against each other. And during World War II, Japan was one of the countries that fought against America. But did you know that Japan did some very bad things during the war?
Yes, they committed war crimes, which means they did things that were not just mean, but also against the rules of war. The Japanese army treated prisoners of war and civilians very cruelly. They did things like torture, murder, and rape. It was very, very bad.
Now, after the war was over, the Allies (which included America) put the leaders of Japan on trial for these war crimes. They found many of them guilty and punished them. But America didn't want to talk about ALL the bad things that happened. They decided to cover up some of the war crimes that Japanese soldiers committed.
That means they tried to hide them, so people wouldn't know about them. They wanted to keep it a secret. Why did they do that? Well, some grown-ups say it was because America needed Japan as an ally against communism. But that's a whole other story.
So, for a long time, the American government didn't want people to know that Japanese soldiers did terrible things during the war. They didn't want to admit that they were friends with a country that had committed such atrocities. It wasn't until many years later that the truth started coming out, and people learned about the cover-up.
But it's important to remember that even though America covered up some of the war crimes, many people still knew the truth. And the leaders of Japan were still punished for the things they did. It's always better to be honest and admit when something bad has happened, so we can learn from it and make sure it never happens again.