This is not surprising though when looking at how these things are usually processed by a society. Not making any excuses for colonialism or prior education on it. But a similar phenomenon emerged in Germany for example, where so many people were morally or otherwise compromised by the Nazi regime that it took until a new generation in the sixties to grapple with their parents’ and grandparents’ actions or lack of action. Timescales vary too; as least as long as the LDP enjoys power it doesn’t seem like Japan is ready or willing to engage with what it did during WWII. This being purposeful is not unique to Japan either, see East German official revisionism about the Holocaust.
Again I’m not trying to minimize the actions of those sweeping dirty history under the carpet, only to highlight that it’s somewhat common in human nature. Part of the reason conflict resolution has trended towards concepts like truth commissions is the hope of resolving a conflict and what the truth is without having to wait for a new ‘untainted’ generation that is willing to critically grapple with its country’s history.