I really must be a rare creature -- and accordingly, get to meet very rare creatures like myself :D
I have met several drug-using South Koreans in my native homeland of Canada. Two were in Toronto, and both were opiate users; one casual [just a young guy trying to be gangsta, really, though I'm sure he enjoyed the OC high! hehe] and one hardcore junky, one of the most hardcore I've met, who IV'ed heroin and hydromorphone which she got prescribed from a Korean doctor [she claimed through her parents networking; I think she might've sucked his dick as an incentive LOL]. BTW, hydromorphone is the main opiate in Canada, it's the heroin of Canada, which is its biggest consumer globally as well. But heroin is common enough in Toronto and Vancouver, and to a very minimal degree in Montreal, and all those 3 cities "commute cities".
Third, I met a third drug using South Korean in the town I was studying -- Halifax. At first, he seemed wary of drug use, and remarked how screwed up it was that all the people -- including the chefs -- that the kitchen we worked smoked weed, like a LOT of weed. I kind of agreed with him [at the time I was staying sober], but said Hey, that's Canada for you. [which is true, the stereotypes are, yes, true, LOL!] In the end, he ended up not only trying weed, but buying it regularly. The he got a giant tattoo of the world map covering his entire upper back to commemorate his journey around the world. NOT KIDDING!
Ha! Besides those 3, I've met like 10 Chinese stoners in the same city. They smoked HUGE amounts, I think they were actually addicted, but they still got through school, albeit with a small courseload [3 courses per term] which no doubt worried their poor parents. As much as I think the East Asian attitude is excessively authoritarian and draconian, I understand the emigrant, i.e. non-Western attitude, the NEED to succeed, since my folks are immigrants to Canada, and the possibility I'd flunk out of school and use hard drugs never even crossed their mind until they found out too late. so I understand the motivation for that "blind" attitude. WW2 really screwed up a lot of places, Korea is one of them. Survival obsession.
Finally, I met a Japenese stoner in Halifax. He was also excessive in his use [like, even by Canadian standards, probably letting loose before re-entering the Dungeon of Sobriety that is East Asia], treating it almost like a narcotic, but that the same time the pot's inevitable hallucinogenic effects did open his mind right up, and we had amazing, lengthy, philosophical discussions about East-meets-West culture, globalization, the end of the world, the difference between our familial cultures, etc. It ws really fun meeting these rare East Asian stoners and being able to telepathically commune with them via the World Herb.
I wrote a bunch about my time in China and the very prevalent drug use there, but that info can 1) be found elsewhere and b) fill up this msg too much. I'll leave it at the "mind-warped" East Asians I've met in Canada. If we're going beyond East East, I've also met a crack-smokin' Filipino in East Canada. He was not a crackhead, but he did steal 40 bucks from me to buy crack. So I guess... a non-obvious addict? [I am also totally not obviously an addict, no one would think it! Comes in handy! But I think it's karma! I commit to a cause beyond the poppy, my brothas! For example: he was a pro-level skater and breakdancer, and I'm a musician and wannabe writer! So there, drug fiend god!]