From a history thread on Reddit:
“After WWII the administration of justice in Germany and Japan were markedly different. In Germany, the Nurenberg Trials were overseen by a joint judiciary made up of the Western European Allies, the United States, and the USSR. In Japan, the Tokyo Trials were unilaterally adjudicated by the United States. This was the first problem. In both situations, the United States acted against the wishes of their allies and blatantly or secretly extradited and exonerated hundreds of war criminals from Germany and Japan. This was the second problem. The third problem, and probably the biggest contributor to the current Japanese cultural and societal ethos and perspective of WWII was the control the US exercised over post-war Japan.
In Germany, the Nurenberg Trials were largely a successful exercise in identifying and prosecuting war criminals. These criminals were tried and punished. While there is still a lot of controversy about the proceedings and the manner in which the prosecution acted – i.e. “perspective of the victors” – there is little doubt that the Nurenberg Trials not only established a precedent for future International Military Tribunals, but laid the bulwark for the development of the field of bioethics as it relates to the human experimentation conducted by the Nazis. US interests in the trial and desire to exonerate some of the more “valuable” Nazis for their scientific abilities were nullified by the influence of Western European and Soviet influence. The key point in Nurenberg is this: criminals, by and large were punished.
In Japan, in stark contrast to Germany, the Tokyo Trials were not only shambolic, but the near unilateral control the US had in the prosecution of the war criminals resulted in a complete mockery of justice. Now let me say this: I am a proud American. I was born in America and have American flag shorts I wear on the Fourth of July as I pound brews to the Red White and Blue, but I am also a historian and a realist and realistically America’s history is not pretty. And in Japan, McArthur essentially held a mock trial where literally hundreds of war criminals either avoided the death sentence or were exonerated altogether. The USSR was responsible for the only punishment and sentencing of Japanese criminals involved with Unit 731 in the Khabarovsk War Crime Trials. While the Tokyo Trials had an “international” panel of judges and prosecutors, there is no doubt that the real prosecutorial power lied with the Americans.
In both cases, the US acted explicitly and with a great deal of subterfuge to exonerate and extradite Nazi and Japanese war criminals whom they felt could contribute to American military and strategic interests. This included one of the pioneers of NASAs rocket program Wernher von Braun. The OSS – precursor to the CIA – and other USA military groups attempted to take these individuals to the US where they would receive research grants, government positions, etc. In Germany, these efforts were largely stymied (but still pretty successful) by the Western Allies and the Soviets, in Japan, these efforts were wildly successful.
Culturally, the influence and proximity of the Western Allies, US forces, and the USSR served to constantly remind Germany of their atrocities and fostered a climate of repentance. In Japan, 70% polled did not know about the contents of the Tokyo Trials, which was even higher for people in their 20’s. Even more alarmingly, there are Japanese that believe that WWII was a war of defense and some just recognize a “degree” of aggression on the part of Japanese. Not only did McArthur and the US fail to pursue justice, but also exonerated/absolved the royal family of all guilt and moved quickly to remove the notion of war guilt from the collective Japanese psyche. Consequently, many Japanese do not see the war with regret, like the Germans do, but view it with a mixture of mild regret and a sort of pride.
Ultimately, the end result was a Germany that is repentant, recognizes its atrocities, and has developed a culture/society that, more or less, understands their role in WWII. However, as [another user] points out, one negative side effect has been a very profound guilt complex that affects cinema and other forms of art. In Japan, the people are not only ignorant of their atrocities, but this ignorance has resulted in a dangerous nationalism not at all obfuscated by any guilt from the nearly innumerable atrocities their country committed from the late 1890s to the end of the Second World War. This is not at all helped by textbook revisions that are not only devoid of the atrocities, but paints the Japanese in a sympathetic light.”