So it's a fairly well known fact that for the most part, post WWII there was a good bout of witch hunting going on, leaders that had dubious responsibility for the actions of their subordinates were punished, at times,for things such as simply not stopping the horrid actions of their subordinates.
However, and correct me if I'm wrong, as I'm Australian, so the view I've been taught may likely be skewed, but from what I've been taught, pretty much the entire Second Sino-Japanese War, the atrocities that occurred there,and further the expansion of the Japanese Empire and the atrocities during WWII, were done "for the Emperor" and it was believed that what was being done,was being done at his will and with his express permission.
Now, the topic of why the Emperor's location was never revealed and a Nuclear Blast dropped on him has been done to death,as it would have essentially martyred him in the eyes of the Japanese people and likely strengthened their resolve.
However, why, after the war, like in a lot of wars, why was he not deposed, tried,and likely executed in disgrace and likely with no honour? It would likely have not been an"honourable" death to be hanged/shot/etc.
I mean, there is a strong history of Monarchs being executed for their actions in war, and essentially in Europe at Nuremberg the leaders of the Nazi regime were being torn apart.
But yet, Emperor Shōwa got away essentially scott free and continued to rule until his death in 1989. sure, his empire was heavily sanctioned,bit he was still Emperor and faced no recourse for his actions.
Three points: