The tragedy is that most of those directly responsible for Japanese crimes against humanity in the 1930's and 40's were never held accountable (in this life); never tried, prosecuted or punished/put to death. As a direct result of this utter miscarriage of justice we have had vocal Japanese deniers of the horrific crimes perpetrated by the Japanese since nearly the end of WWII.
I think only two prominent Japanese were executed for war crimes - Prime Minister Tojo, and General Yamashita for the rape of Manilla. I seem to recall reading that Yamashita was something of a sacrificial lamb because he was a commoner, and getting too far into the Samurai class and the nobility would involve the imperial family, and we needed the Emperor on our side if we were to have a successful occupation.
Soon after the war, the Allied powers indicted 25 persons as Class-A war criminals, and 5,700 persons were indicted as Class-B or Class-C war criminals by Allied criminal trials. Of these, 984 were initially condemned to death, 920 were actually executed, 475 received life sentences, 2,944 received some prison terms, 1,018 were acquitted, and 279 were not sentenced or not brought to trial. These numbers included 178 ethnic Taiwanese and 148 ethnic Koreans.[136] The Class-A charges were all tried by the International Military Tribunal for the Far East, also known as “the Tokyo Trials”. Other courts were formed in many different places in Asia and the Pacific.
http://en.wikipedia.org/wiki/Japanese_war_crimes#War_crimes_trials