The first thing offered to me at Suntory's Yamazaki whisky distillery - the birthplace of Japanese whisky - is a glass of water. It's so delicious it comes as a shock.
Even before the reason is explained to me, I'm asking: why does it taste so crisp, so different?
The distillery is surrounded by beautiful bamboo forests on a mountain - they must be getting to my brain.
"The distillery was built here almost 100 years ago for the legendary water," says Makoto Sumita, who's been with Suntory for 20 years, as we walk past a pond to the tasting room.
Drawn from deep mountain wells and designated one of the best mineral waters in the country by Japan's Ministry of the Environment, Yamazaki's water is also reportedly the inspiration for the legendary Japanese tea ceremony that originated centuries ago.
These days, it's used to make some of the most remarkable whiskies on the planet.