I served in the military overseas in Japan 1956-57. Being very young and not the brightest bulb in the package I ran up against a conundrum. How could the Japanese behavior in peacetime be so opposite of what it was during the war years? I know they were a defeated army, but their overt behavior towards the American military was not what I expected. It wasn't until later in my life that I discovered a simple answer, what you don't know, you can discover by reading. The Jekyll and Hyde of the Japanese war behavior and their postwar conduct was explained in one word, Bushido.
Japanese Military Culture
At the outbreak of the Pacific war, the Japanese armed forces combined modern technology -- including ships and aircraft equal to or superior to their Allied equivalents -- with a military spirit that remained feudal. Termed Bushido (The Way of the Warrior), that spirit gave rise to behavior that Allied soldiers found bewildering as well as barbarous and fanatical.
Based on peculiar perspectives on Confucianism and Zen Buddhism, Bushido demanded unquestioning loyalty and sacrifice. The Japanese soldiers' written code ordered them to keep in mind that duty was "weightier than a mountain," while death was "lighter than a feather." Indeed, death was idealized as something to be welcomed. Thus, soldiers, sailors, and airmen willingly sacrificed themselves in banzai charges, kamikaze aircraft, and kaiten submarines.
Japan's leaders now believed surrender as unthinkable for Japanese and contemptible in enemies, thus justifying abominable treatment of prisoners after prior years of very decent treatment of prisoners (also attributed to Bushido). In keeping with the samurai tradition, they also revered the sword, which led to the beheading of their captives. The International Military Tribunal for the Far East blamed Bushido as a contributing factor in Japanese atrocities.
Atrocities were part of every major Japanese land operation and were directed against both combatants and civilians. The demeaning training and disciplinary regimes in the Japanese services featured corporal punishment and probably contributed to the brutality of their personnel. The Japanese army employed ruses that their enemies considered unacceptable, including wearing enemy uniforms, booby-trapping corpses, and feigning surrender in order to kill would-be captors.
The atrocities could be blamed on other reasons. The Japanese were fighting a losing war, combating insurgencies, and trying to survive amid starvation. However, the atrocities had begun when Japan was winning the war.
Japanese servicemen were repeatedly told that their martial spirit was superior to that of their materialistic enemies, who would eventually succumb. Initially, the combination of Japanese ferocity and skill was frighteningly successful. However, the ultimate defeat of the Japanese discredited their cultural prejudice.