Mizaki Shojiro escaped justice. He was almost certainly guilty of a number of war crimes besides this one, but he managed to avoid being identified in the initial prosecutions and by the time they tracked him down, it had been decided not to proceed with further trials.
“by the time they tracked him down, it had been decided not to proceed with further trials.”
Largely because Douglas MacArther wanted to become known as the father of Japanese Democracy in the same way that his father was known as the father of Philippine democracy.
He saw punishment down the chain of command as counterproductive.