I'm sorry, I got that drink mixed up with one from the ROK. The ginger drink in Japan had welsh (spring) onion (called tamanegi) instead of garlic. It was sweet, but not nearly as sweet as many other things usually are. The garlic drink, although in at least one form sold in Japan, was from the ROK.

Another note- one of the many things I like about Japan is that you can easily find drinks WITHOUT added sugar (for example, sugarless bottled tea is the norm). Unrelated, but um...well at least it's germane to dining buzz.