Wars films that were written in the period of World War II tend to make the Japanese army to appear as brutal enemies. However, the truth of the matter was worse than what most movies can depict. What is viewed on the screen is in most cases a watered down version of the actual and not an exaggeration.
In films, violence is usually depicted as a force that soldiers are engaged in. The military culture took the battlefield survival way beyond the battlefield in real life. In the war in China it was reported that officers made executions a competition and newspapers were publicly following their progress. Barbarity was not a secret, but rather a reward.
Unit 731 was one of the most grim ones. It was a research facility on record. Prisoners were, in fact, tested to death. Suffering of people became statistics, and boundaries of morality were eliminated. This is the reason why many filmmakers do not want to present these events in the literal sense since the reality is more likely to look more like horror than history.
It was not the deed of a few people only that was this brutality. Such campaigns as the policy of the three Alls, kill all, burn all, loot all, made destruction an intentional plan. Whole societies, and not armies alone, paid.
The films such as Letters from Ivo Jima keep the viewers in mind that most soldiers were common men away at home. Nonetheless, personal humanity was within a framework with the ability to be very violent.
Given that full truth was revealed in the cinema without any restraint, many would not have considered the movie to be a war film but history at its worst.
