The island is said to hold more than a thousand wooden vats. The Hishio no Sato district of Shōdoshima, around Umaki and Nōma, is a run of soy sauce breweries behind black timber fencing, where fermentation still takes place in cedar vats. The vats are called koga here. More than a thousand of them survive on the island, and — the harder part — the coopering skills needed to rebuild them have also been kept, which is not true of most places that still use wooden vessels.

Soy sauce has been made here for four hundred years. The board fencing along the brewery walls lets the smell of the moromi out while keeping the sun off the buildings, so the street is scented long before you locate a doorway. Walk far enough and you arrive among the tsukudani makers, where the soy smell mixes with cooking, and the effect is of an industrial quarter on an island an hour by boat from Takamatsu. There is work in soy sauce, in olives and in tsukudani, which gives this island more choice of employer than most.

A wooden vat is inherited together with the organisms living in it. Scrub and sterilise one and the flavour changes, so a vat that has been in use for a century holds a century of accumulated microbial life in its timbers, and the number of vats a district owns is therefore an asset in the most literal sense. A thousand is a count of equipment, and equipment can be replaced with money in a season. It is also a count of elapsed time, and that second number cannot be bought at any price, which is the whole of why the coopering skills mattered enough to keep.