Hmmm...  In my experience, the way Japanese girls act in porn is *very* different than the way they act in reality.  Japanese girls, and most Asian girls for that matter, are not submissive.  Not surprisingly, Japanese porn reflects fetishes prevalent in Japanese culture and Japanese men are turned on by JAV girls who act very innocent.  Because Japanese society is also very formal and conformist, some of their porn tends to feature a lot of what we would consider degrading situations.  The girls squeal and cry because for the most part, they are not supposed be enjoying what they're doing.  There are a few JAV stars that do not act this way (e.g. Riko Tachibana) that are much hotter to watch, IMHO.