In movies that show the Pacific and Eastern Fronts such as Enemy at the Gates and Letters from Iwo Jima the Japanese and Russian forces are always doing mass infantry assaults and losing absurd amounts of men.
Is this really what they did?
And in the case of the Japanese why would they do this if taking to ground and defending fortified positions were much more effective against the US?
Imperial Japanese forces did have men committing to seemingly (and sometimes were outright) suicidal attacks that had no tactical or strategic merit to them.
But it's important to realize under what conditions these attacks were made. Suicidal charges were not made by well supplied, rested units that were in good contact with the chain of command.
They were always conducted by soldiers who were burdened with the wounded, weakened by disease and/or starvation, lacking ammunition or even weapons, and often cut off from their own lines and no way to contact superiors.
Most commanders tried to prevent their men from committing to futile banzai charges because it seemed just as wasteful and terrible decision making from the Japanese side as the Allied side.
This is a big topic and I wrote extensively about it here. Feel free to ask follow up questions.
http://www.reddit.com/r/AskHistorians/comments/33gpww/where_did_the_myth_of_the_soviet_union_throwing/ The question regarding the Soviets was recently asked here.