There's actually something of a stereotype that Japanese places will give you unreasonably small portions of water with meals. (Dogen plays off this in some of his videos.)
But then, I think it's only been Americans I heard this from, so.
In both my trips to Japan (one recent, one 20yrs ago), I never noticed this, and I think I drink a lot of water in general, and especially as a tourist because I'm doing much more walking.
The free water cup in a lot of places in the US is like a 6oz slosh now.
Ha! I hadn't heard of this before, so it caught me completely off guard.
The coffee was the one that really surprised me. Order a coffee and get a 6-8oz cup. With nothing on the menu to indicate you can get a 12-16oz. Was surprising. (Not bad, mind. Just surprising.)