The experience in attending k-12 in Japan is different from American. Expectations in class and the people around you are different. As one poster said "try not to stick out". Is an appropriate description of what the experience is like Japanese schools. If you are overly stupid or smart, extremes of the spectrum means you stick out.
You must raise your hand and be able to study quietly in Japan. American schools tend to be more discussion oriented and want their student to be outspoken and ask questions. It's just the style.(I'm more American at heart, so American style suites me best).
One thing that is notably bad in Japanese schools is the bullying. There is bullying in America, but not quite to the extent Japanese schools have been known to have. This is not everyone's experience, but it's something you should know about.
COLLEGE:
is a totally different case.
In American schools: "we work hard but we play hard" is the general tone. Of course we have slackers and social hermits, but on a whole there is usually a balance. Our teachers,are generally again...more easy going and discussion based. If you talk to them they might be liable to bend the rules for you(like a late paper). However, the expectation of quality of work is much higher in America I think. This varies from teacher to teacher of course...But on a whole this is what you can expect from a "good" professor.
In Japanese schools: It's play time! They've worked really hard throughout k-12, go to juku(afterschool cram school) so that they can get into a good school. Now, they join circles and clubs and DRINK DRINK DRINK. I went to Sophia University, which is a pretty well known school in Japan...it's like a Stanford image equivalent. Of course, I was on the foreigners department, but when i joined circles...it's seem to show that this heavy drinking and playing was a schoolwide consensus. University is not taken as seriously in Japan, grades don't matter...it's just the title that you gain from going to the school.
I prefer American Universities, I felt that it was better at teaching me what I needed to learn in my degree. I enjoyed school in Japan from the experience that I gained outside of my academic life, and I still recommend it..if you are considering it. But if you want to work in America, stick with an American degree.
Hope I answered your question.
Here is a blog post about my overall university experience in Japan. As well as personal recommendations:
http://wanderingabc.blogspot.com/2008/08/how-tos-11-attend-universitycollege.html
-WanderingABC