It is a popular view that international war crimes tribunals are a tool for social transformation and reconciliation after conflicts. According to advocates, one of their strengths in this regard is the individual punishment of criminals, which is said to achieve justice for victims while avoiding the collectivization of guilt. This is also said to have the effect of endorsing the transformation of the nation by freeing it from the burden of collective guilt while detaching those responsible for war crimes from the society concerned and eliminating their political influence. Does individual criminal punishment achieve these? And is the de-collectivization of guilt through international trials desirable for post-conflict social transformation and reconciliation? This article addresses these questions by focusing on the impact of the Tokyo International Military Tribunal, which is analyzed through the ways in which it has been perceived in post-war Japan. It argues that the Tribunal's punishment of wartime leaders produced an ambiguous effect on the Japanese people's sense of war guilt and responsibility, which in turn became an obstacle for the nation to achieve reconciliation not only with its former victims but also with its own past. The article questions the assumption that international criminal justice can promote social transformation and reconciliation.