Not going against what IG and 'Oni said, but fear of being caught by the authorities just doesn't really bother any of the (Dj's, club owners) guys that I know who regularly smoke. Yes the penalties are harsh, but the chances of getting caught are pretty slim... well unless the club you're at gets randomly raided (which is rare - but happened to 'The Underlounge' here in Osaka just 2 months ago, multiple arrests for possesion) or you're noticebly smoking weed outside or in public view. I'm not saying "it's ok!!!", but just saying that more people talk about the dangers of getting caught with weed than people actually getting caught... or maybe my mates are just really clever about it?