Why were Japanese like that in WW2

TL;DR

Japanese wartime brutality stemmed from Bushido's warrior code, which glorified self-sacrifice and treated surrender as shameful disgrace deserving contempt.

Key Points

• 1.Bushido, Japan's ancient warrior code, was the root cause of wartime behavior. Formalized during the Tokugawa Shogunate, it emphasized self-sacrifice, reckless bravery, and unquestioning loyalty; it was repackaged for WWII with Emperor Hirohito replacing the feudal shogun, and instilled through brutal school militarism including beatings and forced exhaustion.
• 2.Surrender was culturally inconceivable, producing staggering death ratios. Japanese soldiers died at a rate of 120-to-1 versus captivity, compared to 3-to-1 for Allied forces; the largest banzai charge at Saipan on July 6, 1944 saw ~4,300 soldiers die rather than surrender, with Lieutenant General Yoshitsugu committing seppuku beforehand.
• 3.Allied POWs faced a 37% death rate under Japanese captivity. Japan never ratified the Geneva Convention — some officers called it the 'Coward's Code' — so the 80,000 troops captured at Singapore in 1942 were treated as dishonorable animals: starved, beaten, used for bayonet practice, and executed for minor infractions, versus a 1.2% death rate in German camps.
• 4.The Nanking Massacre and Unit 731 exemplified brutality toward civilians. Between 100,000–300,000 Chinese were killed in Nanking in late 1937; Unit 731 performed live vivisections, amputations, and weapons testing on Chinese and Korean prisoners, with organs removed from living subjects to track disease progression.
• 5.Japanese fear of Americans evolved from contempt to genuine terror. Pre-war propaganda dismissed Americans as soft and lacking Bushido spirit; but by late 1943, diaries recorded dread at America's industrial inevitability — 'It's like fighting the tide' — and Marine Corps propaganda portraying them as prison-recruited sadists convinced soldiers that surrender meant torture.
• 6.Wartime propaganda caused mass civilian suicides, most tragically at Saipan and Okinawa. Told Americans were demons who would torture captives, ~13,000 of Saipan's 20,000 civilians died, with hundreds jumping from cliffs hand-in-hand; five-year-old Koyu Shiroma survived only because his clothes snagged a branch; at Okinawa, 100,000–150,000 civilians perished, validating fears that an invasion of Japan itself could kill millions.