Mizunara oak, it has a curious ring to it. Scarcer than European and American oak, and much more expensive, its story is deeply rooted in Japanese history. At the end of World War II, Japan faced shortages of medicine, food and other daily necessities. The lack of imported casks to age whisky was the least of the country's problems. But the spirit was popular with the occupational armed forces, so whisky makers had to do something. Distillers began to use the native oak, mizunara.