This is beyond moronic. Firstly, just because you invent a strawman doesn't oblige anyone to debunk it. Secondly, I think you'll find that Japanese American internment is exceptionally well documented, there is a substantial literature on the subject, with Wiki providing a good starting place. There simply aren't any "missing" Japanese Americans.
Isn't the holocaust exceptionally well documented with a substantial literature on the subject? I think the standard answer to your sort of reasoning is something like: "Oh. Because there were some survivors that proves nobody was murdered. Then you should have no trouble finding them. Hop to it!"