At the end of the Pacific portion of World War II, Japan was occupied by the wartime Allies, and Gen. Douglas MacArthur, the Supreme Commander for the Allied Powers, began a cleanup. Many were the calls for reform and much was the censorship.
Economics, politics, jurisprudence, all were swept clean by the SCAP broom, and yet its promulgations only rarely affected the arts. Film and literature were subjected to some censorship, but painting, drawing and printmaking, hardly at all.
Various businessmen were tried for supporting Japan's militaristic wartime policies, but painters who were equally complicit were never called to account. Indeed, such wartime activities are even now usually left out of their official biographies. Taikan Yokoyama, who had even (among much else) delivered lectures on the spirit of Japanese art to visiting groups of Hitler youths, continued to exhibit after the war just as though nothing had happened. (It is worth remembering, however, that in their wartime military support Japanese artists were little different from those abroad. The dubious aims of France's Vichy government, for example, were actively supported by Andre Derain, Maurice de Vlaminck, Aristide Maillol and many others, all of whose reputations survived unscathed.)