It doesn’t matter how long you make them read Lenin and break rocks in the gulag, the second you let them out they’ll see an AI generated meme from a CIA holdout posting from a bunker somewhere and immediately revert to being a burgerbrained fash.
I think we need to just dump them on an island somewhere and put them under continuous naval blockade and internet blackout till they revert to a Hunter gather society.
Because it destroys their ideology framework. They spared them not because they “were better than that” or because the soldiers “deserved it” but because in the minds of the japanese fascist any violence was justified and will be justified because the enemies are violent brutes who will mercilessly destroy and brutalize the Japanese.