The comments related to thinking versus actual brains is an interesting one. The Japanese have published some books stating that Japanese brains are different.

One of the few real differences that I am aware of is the common missing enzyme in the liver for processing alcohol which quite a few Japanese seem to have. Of course, some Japanese drink quite a lot and have built up a tolerance, whereas other ones drink a small glass of beer and will have a flushed face and sometimes exhibit symptoms of a drunkard. It seems some Chinese have this same biological trait as well, so it is hardly unique to Japanese, but much more common than in most other countries.

Another difference is sometimes a higher percentage of double jointed individuals, especially in the wrist and ankle joints. I often see young women here standing with their legs twisted around in positions that I wouldn't try.