The rice is Thai. A spirit made in Japan, from Japanese water, by a Japanese method, and the grain comes from Southeast Asia. Long-grain rice is hard and stays separate, which lets the black koji mould push its threads through it. That is the entire reason, and nobody has found a better one in five hundred years. Where the grain grew has never been the question; whether the mould can get through it has.

Black koji produces citric acid in quantity. Acid keeps other organisms out, which matters in a place that is hot and wet for most of the year. The technique is said to have arrived from Siam some time in the fourteenth or fifteenth century, when the Ryukyu kingdom was trading across the region, and to have changed very little since.

Anything aged three years or more is kusu. There is a practice called shitsugi: you draw from the oldest jar, then top it up from the second oldest, and that one from the third, working down the line. The gap left in each jar is filled with something slightly younger than itself.

The name is now protected, so only spirit distilled on these islands may be labelled Ryukyu awamori. The jars are never emptied and never replaced. Only the contents move, a little at a time, downward through the years.