This has been widely known within military history circles for quite a number of years. MacArthur brought a very quick end to the war crimes in Japan because we were concerned about the Soviet and Chinese threat in the Far East and we wanted to rehabilitated Japan quickly so that we had them as a strong ally.
Since there were very few public war crimes trials and even fewer ended with an execution, the Japanese Public never understood what their government did during World War II. For the most part, they are still in denial.
You are correct. Their history books still downplay or conceal many of their activities.