Yeah, I live in Japan, am 17 years old and no problem. Not that I have drank, I haven't drank anything really, try to stay away from trouble actually, but I sometimes go to Izakaya or something with another exchange student who is 23 and have never been carded. They just ask me what I'm gonna drink, to which I always respond to water.

It would be no problem regarding buying alcohol, I haven't tried nightclubs, though.

Mauricio