The same way that Americans, post WWII, refused to accept that American downed flyers were carved up, kept alive while being carved up to preserve freshness, cooked, and eaten by those stinking japs...
I heard of Unit 721 when most people hadn't.
As well as stuff from the Rape of Nanking.
But I've never heard of this one.
Do you have a link so I can read up on it?