They are grown in the dark. Ordinary garlic chives are covered as they come up, so that they never green, and what is harvested is pale yellow the whole length of the stem. The technique has a name of its own in Japanese horticulture, and it amounts to withholding light on purpose.

Without light the fibre stays soft — soft enough that the stems can be eaten raw, which is not true of the green kind. Chinese kitchens have prized it for a long time on exactly that account. The smell is recognisably chive, but the sharp edge has gone out of it, and what reaches you first is sweetness.

For ohitashi they are dropped briefly into salted boiling water, then dressed with dried bonito flakes, a little chilli and citrus soy sauce. Nothing else. Anything more elaborate cancels the thing you paid for.

Cultivation is said to have begun around 1872, at Musa and Tamagashi on the edge of Okayama city, and to have spread outward from those two districts. The prefecture now accounts for roughly seven-tenths of national production. One decision — to keep the sunlight off — turns an ordinary vegetable into a different one, and it took a century and a half for anybody else to bother.