Sadly I know about that. (As another comment: Sometimes you hear that these unethical experiments gave humanity insights that have been valuable. But at least in general that is not true, not lastly because it was shit science by shit scientists to begin with. )

I just don’t know the extent of these things being known in WWII Japan. I would assume it was similar to Germany but for Germany I have read enough to know it for sure that it has been known at the time and not just for a chosen few.

And adding to that: People saw what happened to their Jewish/Romani/Disabled/Communist/Queer neighbors. They worked in the clinics where disabled children were selected and sterilized or (sent off to be) killed, knew the police men who rounded up homeless people etc. And people came back from concentration camps as well. Some people did time there for ordinary crimes. German citizens incarcerated in concentration camps even had to pay for social security while incarcerated, so that their insurance history wasn’t broken afterwards.

I don’t know about specific programs like Unit 731. But in general: People wrote letters. People came home and talked to their spouses. Concerning the Germans: A lot of people were involved. The Einsatzgruppen were staffed by ordinary police. The Waffen SS fought alongside the ordinary Wehrmacht which had their ugly share of atrocities. All these people wrote and came home and talked. And the concentration camps on German home soil were not isolated. People saw what happened there. People worked there as civilians. People who say the general public didn’t know are lying.

FELLOW HUMAN! I LIKE HOW YOU – ON PURPOSE – USED THE STYLE, STRUCTURE AND RHYTHM THESE SO CALLED AIS USE. NO REAL HUMAN WOULD WRITE LIKE THAT, RIGHT? I‘LL GO ON DOING PERFECTLY HUMAN ACTIVITIES, LIKE TALKING WITH OTHER HUMANS PETTING SMALL FURRY NON-HUMANS AND EATING.

Yes, apparently there’s a new cosmetic surgery technique called deep lift. And this is the result.