For a truly educational, fascinating, harrowing & overwhelming experience, Changi museum in Singapore is probably among the very best. Much more below, but first ...
I find I'm drifting towards crying as I write this - somewhat but not totally to my surprise.
I'll note up front, as it may otherwise not be obvious, that I try to consider all races as equals.
I understand that there is much that I do not understand.
I try to hate none.
Japan and the Japanese I enjoy and certainly do not hate - and certainly do not always "understand" :-). I've spent a few weeks in Japan long ago and would happily spend much more.
Based on what I hear them reported as saying, some of the modern Japanese ultra-nationalists I perceive as being too close to their long ago forbears. Hopefully they will never get a chance to prove me right.
Changi museum in Singapore probably goes a long way towards addressing your requirements for one area of Asia in detail and much of Asia in general. It covers Singapore and (then) Malaya, plus to a variably decreasing extent with distance, Indonesia and the various Pacific Islands. It still does quite a good job of providing material on those areas but for Singapore / Malaya it is just utterly overwhelming.
What is seen in Changi is unrelated to the lives of the very very major part of the Japanese people today. But, alas, not quite to all. On leaving Changi it may take a few minutes to restore ones normal perspectives. Brave the Japanese tourist who ventures there - AND deserving of great respect for doing so.
I do not think the museum is overly nationalistic or unfair. It is hard to give a historically accurate tale of unrelenting horror and evil without suggestions of bias and imbalance. When what is being described is so very imbalanced it's hard to be completely sure that strict impartiality has been observed. It's reasonable that accounts from the times concerned are one sided and a historical record of these simply allows them to tell their story.
If you want to hate Japanese people, don't go.
If you want to understand ultra Japanese nationalists, this will just show you it's impossible.
If you want an example of people behaving in manners which would be anathema to most current citizens of Japan, Australia and most other countries, and a sobering warning of how bad mankind can get, it's probably among the best examples you'll find.
In some respects it's not up to Nazi death-camp standard (I'm glad to say). But, in that it reflects the open and common practice of most japanese troops at the time, regardless of why, it's extremely harrowing.
Historically accurate? I think so.
Biased? It can't avoid being but it seems a very fair and open record of reality, regardless of why.
I'd forgotten how very very very impacting it was to look through it (and that was only about 6 months ago) but by now I am crying as I write this.
It gives a good account of the treatment of locals - and some stunningly positive stories of the personal sacrifices that some of the locals made on behalf of the allied prisoners to supply them with food and medicine when possible.
If you are serious about wanting to see an extensive record with much historical material I'd be surprised if there was anywhere that covered their part of the subject substantially 'better'.
The Canberra war memorial museum is utterly awesome (and they do after all have Baron von Richtofen's compass and joystick, an Me262, a Churchill tank, a can-opened Japanese mini-sub, an 80+ raid Lancaster and much much more) but for the specific subject I did not find anything that approached Changi. I could easily have missed it as you'd need far longer than I had available to do justice to the cWMM, but Changi would be 'hard to beat'.
For a reasonable idea of what you are liable to find read the early parts of Nevil Shute's "A town like Alice" - the part set in Malaya/Indonesia (book takes liberties in geographical location of a real life event). That's a glimpse. Then visit Changi. Take a handkerchief.
I have a number of photos of selected material. Not on a website. I could post some to a web page if of interest. But the Changi site may do better. I've not looked. Sniff ...