Hey Simon! Glad to see this post and I'll try to clear up any questions you may have!
For starters, I'm not Japanese so I don't know everything, I haven't lived in Japan all of my life, in fact I only lived there for 3 months, but most of my information comes from my studies (I'm an East Asian Studies major), my numerous friends who are Japanese, and my experiences that I had while there.
Japan is just like any other country, it's not perfect, it has its good point and its bad points. Some people love different aspects of the culture more than others and some people simply can't stand it, it's all about the perspective of the person. A lot of people lose sight of this and go to Japan (or any other country really) and expect everything to be exactly like they thought it would be or are shocked because they didn't know what to expect. People who go to another country for such a short period of time, including myself, go through what I would call a honeymoon phase with the culture and the people. Everything is seen through rose colored glasses and when something big happens to break the glass, you begin to wonder why things changed and you become confused and potentially hurt from it and the image itself is completely ruined. Don't let this ruin your image of Japan, don't be confused because of a few things you see or hear from others. If you have questions, seek answers (just like you did here!) Even here though, you won't find solid answers to all of your questions, your answers will be formulated on how much information you gather from others and what you choose to believe based on your experiences mixed with the opinions from others. That being said, I'll give my opinions on the issues you've brought up. Some of which I can't really make much of a reply to myself because I haven't experienced some of these issues.
Yes, Japanese people are VERY polite even if they don't want to be. This has two names,
honne and
tatemae This is the private and public stance of a person, we have this in our own cultures, but it's actually more intense in the Japanese culture to ensure peace and harmony. This is the concept of keeping a face that avoids confrontation with the general public, you hide your true feelings and intentions to prevent hurting another. It isn't meant to be seen as being two faced, but really, the person just doesn't want to cause problems or hurt anyone's feelings, so unless you're in their inner group of friends and family, there will be that public face presented to you. There are ways to detect true intentions and feelings of someone, but it's more through subtle body language and other small factors that takes a lot of getting used to. If you'd like to learn more about that aspect, there's a good book to read called
The Japanese Mind by Roger Davies that goes deeper into the topic.
Along side this topic, the topic of racism and arrogance works in with this as well and really it doesn't have a whole lot to do with racism as much as you're obviously not within their close personal circle. The Japanese people have a tendency, more so with the older generations, to keep to themselves, the younger generations are more accepting of foreigners but really, if you think about it, that's how it is world wide. The older generations of most countries, mine included (America) are less accepting of foreigners, we complain about people coming over the borders taking our jobs, etc. It's stupid yes, but that's because of education and a lack of interaction with people we see as being different. Statistics show that a good percent of Japan's population is older people, so they still have quite a grasp on how the country is ran and how people think and act.
Here's a few charts to show what I mean, if you're interested.
The traditional ways are starting to soften to foreigners and depending on where you go, people will be much more polite to you. I found while I was there, people were more polite to me in the heavily populated cities compared to the country side (where my university is located). Because people in the cities have more interaction with foreigners than people out in the country. For your friends though, it is sad that they were treated poorly compared to you, but I've noticed a trend that Japanese people just love Westerners and if they see someone who's white, they automatically think they're from America, just as people in the West see an Asian and think they're automatically Chinese (this irritates me, but not a whole lot can be done about it except to inform them). My hypothesis on why Japanese people are more welcoming to Westerners is because they know more about America and Europe than any other part of the world because of a rising interest in pop-culture and political relations.
Onto the porn thing, in MY experience, Japanese porn is actually not that popular, yes, teens get a hold of it, but you know, American boys get a hold of play boy all the time. I have to agree with something someone said on this thread about the different types of porn. Yes, Japanese porn is weird, but other countries come up with their own weird fetishes as well, so we can't really go around saying Japan is all about porn, it really isn't. In professional and public standings, this kind of topic is very offensive and a lot of Japanese people will refuse to acknowledge it out of disgust because a few holes in the wall ruined their entire image. Just like here in America, Japan has specific places for these kinds of things, some of it is unfortunately more public than it is here, but that's merely because parents get more upset over how public it is here. I actually went with one of my friends to one of those stores while we were out on a shopping trip. It was actually not an easy place to get to, those places are really well hidden in my opinion so though you can find rinky-dink porn in a local book store, the major porn is more hidden in red light districts. So porn isn't as well thought of in Japan as people think it is. By the way, thought I should mention, I went against my will and stood outside the entire time. x.x;
Finally, the whole war issue, I never really got into it with anyone, but I will have to go with what someone said in a previous post. This topic will be more touchy for the older generations compared to the younger generations, as for war crimes, I think it's just best to let things go, it's in the past, learn from it, but to be asking for apologies now is kind of useless. They bombed Pearl Harbor, then we dropped the A-bomb on them, it was a sad series of events, it shouldn't have happened, but it did. The important thing now is to move on, they're our allies now and that's what's important.
Don't let these few things hinder your image of Japan, your impression will change regardless of how much you learn about Japan or any other country, the thing is finding the beauty in the culture in both the impressive and not so ideal qualities.
I hope this helped, and sorry that it's so long. I hope you return to Japan one day to continue to develop your impressions of the culture. <3