Why is Japan never criticized for WW2?
No one has ever really taken Japan to task over WW2 in the same way Germany has been or even the British have been over the British Empire.
The official policy in many aspects of Japanese public life is to deny the Nanking massacre and to act extremely defensively towards anyone who suggests that Japan was in the wrong.
Japan's attitudes haven't really changed that much today. Chinese and Korean residents of Japan are still looked down on as second class citizens and often have difficulty in applying for Japanese citizenship.
Japan's history is one of the most violent and destructive in the modern era and yet compared to Germany and the UK, they have got off lightly.
No one ever judges Japan in the light of WW2, yet Germany is judged in the light of WW2 all the time and the UK is judged in the light of the British Empire.
The fact of the matter is Japan remains a racist country that refuses to accept responsibility for its past atrocities.