A couple of points on the question “Did some Japanese soldiers hold out for years after WWII?” Essentially, early in the war Japanese soldiers were transported to islands to defend to the death, with no hope of evacuation or rotation out until their final victory in the war. With the course of the war it was essentially a death sentence. Very quickly it became impossible to resupply these island troops, and along with the harsh conditions of service under traditional officers the soldiers essentially turned savage. Given that mindset, it’s not a matter of ‘holding out’ but more a resolve to remain in the field after becoming disassociated with civilization. It became more natural to live in that certain way. Interview of the ‘holdouts’ establish this, and additionally there was the expectation by them that if they were ‘captured’ they would be killed. Further, while there were very few prisoners taken, this was less a product of ‘Bushido’ than it was of the systematic execution of captured or wounded Japanese soldiers by the Allies. The few captured soldiers was taken specifically for their military intelligence value. The Allies established special teams, staffed with bilingual Japanese-Americans to convince the more compliant, and therefore more forthcoming and valuable intelligence assets, to give themselves up. Surrendering or wounded Japanese, of which there were many, were executed immediately because of their reputation for terrible atrocities in China, the Philippines, Guam (the American territory occupied by the Japanese), Burma, etc. as well as the low opinion Allies had of them after Pearl Harbor, in addition to the overt racism that existed fed by the media. One will note that tens of thousands of Japanese prisoners were taken in the China/Burma theater before the end of the war where entire units of troops could surrender, too many to simply execute. After the final Japanise surrendered, there were essentially over a million Japanese prisoners. It would not appear that ‘Bushido’ interfered with them laying down their arms. Indeed, the ‘holdout’ Japanese did not engage in military action after the war, either.
Extraordinary claims demand extraordinary evidence.
Paragraphs are your friends.
Are you referring specifically to the Rape of Nanking, the Changjiao massacre, Unit 731’s human experimentation or one of the other countless atrocities the Empire of Japan committed in China?
Welcome to the Straight Dope Message Boards, Hestheone, we’re glad to have you here. When you start a thread, it’s helpful to other readers to provide a link to the column you’re talking about, saves searching time and keeps us all on the same page. I’ve edited a link into your first sentence, no biggie, and you’ll know for next time.
You will also see that most of our members want evidence/specifics to back up generalizations. 
That can be annoying, but it’s also one of the ways we’re different from many other message boards. Anyhow, as I say, welcome!
So, if not Bushido, it must have been some other factor that led to the death of 231 Japanese soldiers in the Cowera break out? Nippon Television didn’t consider the theory that they were all murdered by Australians. “Ano Hi Bokura no Inochi wa Toiretto Pepa yori mo Karukatta”.
Unlike soldiers in the Allied forces, Japanese soldiers were encouraged to keep diaries. Of course, they could have all been lying to their diaries, or the diaries could all be forgeries, like the American Moon Mission and the Obama birth certificate. Failing that, they form a historical record of the motivation and experiences of Japanese soldiers.