as far as i know, alcohol isn't considered the curse it is in western culture (neither is sex). there are certainly non drinkers, but they usually pass it off as being "weak with alcohol". that doesn't mean that they are abstaining as such, but it might be used to mean that (another language nuance), so who knows really!
"osake" is used in rituals (such as sumo) so partaking is part of the culture, maybe a little different from the boys encouraging you to drink at your first job at 18. for men who don't or can't drink, the company drinking parties (not optional) are quite tough i believe.
it is also laid out at temples. not taking the communion wine might be seen as a little too strict in most christian denominations, i guess it's the same thing.
the point is, most non drinkers will order a drink and sip at it for hours while everytone else gets blistered.