From: Near Portland, OR
The increased willingness of Germans to sacrifice themselves is, IMO, more a sign of fanatical leadership combined with a culture of strong military tradition.
As Alfred pointed out, the war on the Eastern Front was a no quarters fight (thanks to the Germans, when war started the Russians said they would abide by the Geneva Convention, but quit when the Germans didn't). If surrender is not a viable option, soldiers often to fight through more hopeless situations than if it is. Americans in the Pacific tended to hang in a fight to more extremes than they did in Europe. The Marines are famous for it, but US Army troops did too. When surrender is a worse option than death, people will often go through more on the battlefield.
The Russians were, if anything, more suicidal than the Germans. The Commissars made sure of it. When the fight was cast as for the survival of Mother Russia, it spurred a lot more willingness to fight from the troops.
The Japanese were a very different culture than the western powers with very different motivations. The culture was built around the story that the emperor was a god on Earth and when the military took over the government they corrupted the old Samurai Code into the Code of Bushido which was pitched as a sort of Samurai Code for everyone. Admiral Kurita was one of the few Japanese commanders who was not known for suicidal bravery. His father was a historical scholar and Kurita grew up reading the classics from Medieval Japan. He was one of the few of his generation or younger who fully understood what the Samurai Code was and how it had been corrupted.
In Japanese Code of Bushido culture dying for the emperor was a great honor that promised rewards in the afterlife. On the other hand, being taken prisoner was the greatest disgrace a soldier could have. The disgrace was so strong that the few who had been taken prisoner who returned to Japan after the war were almost universally shunned, even by family. Many former POWs chose to go somewhere else to live out their lives.
No other major combatant in the war had such a fervor in their troops. The Russians and Germans succeeded in getting a degree of fanaticism higher than what was seen in the Anglo-American armies or the Italians. But it never matched the Japanese, nor did it have the same roots.
My 2 cents.
WitP AE - Test team lead, programmer