The ordeal of the women who were coerced into sexual slavery by the Imperial Armed Forces during the 1930s and 1940s is beyond dispute, as is the responsibility of the Japanese state for these deeds.
After the war, when preparations were made for the International Military Tribunal for the Far East, the Allied Powers knew that these atrocities had been committed, but for various reasons decided not to pursue them.
One reason was that American soldiers of the occupation enjoyed the brothel system the Japanese government had set up for them even as American authorities knew that women were being coerced into prostitution. The plight of women during and after the war was of little interest at the time.