All school curricula are ideological: what they contain reflects society's, or at least the elite's ideas about what is important. Aborigines used not to feature in Australian school history books; Australia was first settled in 1788, and there begins Australian history. Nowdays, Aboriginal history is integral to the curriculum. Countries and governments make very deliberate choices about what is taught and what is excluded. The NSW history curriculum still has too much focus on national studies. Learning Japan, or China, or Germany or any other of the multitude of national studies that are available means broader international trends tend to get glossed over.
The Japanese and American practice of dividing history according to Domestic History and World History is also artificial. When I teach Japanese history and look at Japan's interactions with other countries, students can be perplexed because it's not "Japanese history" it's World history. Currently the Japanese national curriculum does not prepare students for engaging with the world, even though there is increasing talk of "globalization'.
There are two major problems with the Japanese history curriculum. The first is the approach. History is still taught as a subject of facts to be regurgitated: who, what, where and when. Names, dates, places. Why and how are far less important, and again are taught as facts. There is little in the way of "higher order" skills such as evaluation, analysis, or hypothesizing / (re)creating. Furthermore source analysis is not included. There is nothing as far as I can see in the system that would for example when studying the dropping of the atomic bombs try to weigh up the moral arguments or the practical arguments. It's easier to simply say naive Japanese were deceived by their government and the Americans dropped the bombs which caused untold misery. It goes across all topics though, not simply the war.
The second issue, which gains a lot more coverage is the content. If I were writing Japan's national curriculum I'd be conscious of the fact that peace in the region is currently fragile and would have regional respect as a goal. This is ideological, but, like including topics to promote multicultural harmony in Australia, it'd be working towards a stable, peaceful society and region. Currently Japan's curriculum is too national centric - building a romanticized image of Japan. Japan as a country of superior culture, customs, and flowing on from that people. (Again, this is not something Japan is alone in doing.) Relations with SEA and to some extent China are defined in terms of Japan being benevolent. Japan is the kind regional aid donor. This is very nice, and students often say they want to go and rescue poor children, but they fail to ask why are they poor, and they fail to see the needy in Japanese society. IMO Japan should put more emphasis on historic connection of the region Korea and China but also including Thailand, the Philippines and Vietnam where there were sizable Japanese communities in the pre-Edo era. Currently I don't think there is anything much in the curriculum about migration theories from the south and through Korea. There's little sense that the Japanese were not always "here". Along with this, there is also nothing much on the displacement of the Japanese native Ainu. Few students know anything much about Japan's invasion of Korea in the 1590s - ignorance that is unimaginable to Koreans.
Problems tend to be things that are outside Japan. As I've written before, Gandhi and Martin Luther King Junior are favourite topics in school textbooks as they struggle for rights against racist white domination. It's true and it's a good topic, but I've yet to see it brought back to Japanese society and question the struggle for rights of Zainichi Korean or Ainu people. There is little to question gender stereotypes either.
If I were writing the curriculum, I'd also include frank assessment of the rise of modern Japan and the origins of the war. I'd look at imperialism being an international trend, that Japan got swept up in, and how Japan evolved from being a target of western imperialism to being an aggressively imperialist country. Looking at the past honestly means understanding what happened, and why; it doesn't mean endless self flagellation of things that can't be changed. Understanding how Japan went from being an ally of the US / UK / France in WWI to being an enemy by the late 30s, is really important for mature understanding of history and for understanding the neighbours. There's a tendency in Japan to see itself as a victim. (I actually had a student say that yesterday - until she saw the movie Pearl Harbour with her grandfather, when she was in middle school, she had no idea that Japan had attacked other countries. She had only known about the atomic bombs.) It's not just the ministry of education but an omission of society. Few students know anything about the Thai Burma railway, Unit 731, the death marches in Borneo and the Philippines. They also know nothing of local massacres / slave labour during the war. I have given students a list of wartime incidents - Singapore Massacre, Hanaoka Massacre, Thai-Burma Railway, Sandakan Death March, Bataan Death March, Unit 731, Manilla Massacre, and the Joetsu POW camp (this is a little different, but it, like Hanaoka is a good example of post war efforts for reconciliation). I've never had a student know more than three of them. Few students have any idea that Japan bombed Australia. (It's possible that Australian students don"t know it either...) Most students know Japan did "bad things" but no sense of what or how or why.
Several students said yesterday they have been overseas and felt very ignorant when asked questions about Japan's military and political past and present, They said that they had absolutely no idea about it. I feel really bad for them. The curriculum doesn't prepare them to engage with people from other countries at all. They look ignorant, (they are ignorant) but unless you've had a catalyst to look more deeply, it's not really reasonable to criticize them. The current education minister believes bad parts (truth) in history shouldn't be taught because it makes students feel worthless. Instead they should be taught patriotic history. I couldn't disagree more.
Failure to teach history honestly is one of the greatest disservices the education system is inflicting on Japanese society. If history is sanitized, the foundation for understanding the present has been erased.