The fermenting floor is called a bed. The Ai no Yakata is the residence of a merchant family that dealt in indigo, kept as a museum with the working areas left intact rather than cleared for display. Cut indigo leaves were heaped up to ferment in a space called the nedoko — the bed — and the name is entirely accurate: the material is laid down and allowed to build its own heat over weeks. Fermentation raises the temperature enough that this was sweated work even in winter, and once you know that, the height of the ceilings in the building stops looking decorative and starts looking necessary. The floors are earth for the same reason, and the doors are placed to move air rather than people.

Dyeing can be tried on the premises without much ceremony. Cloth lifted from the vat comes out green and turns blue in the air as you watch it, over the course of about a minute, and the first time it happens you will not quite believe it. Central Tokushima is twenty minutes away by car, and express buses reach Kobe and Osaka in roughly two hours. Fields surround the building and the setting is quiet enough that the house is audible.

The colour is not settled at the moment of dyeing at all, whatever the word suggests. Indigo made this area wealthy before synthetic dyes arrived, and the scale of the house is the evidence of how wealthy. The fields around it still grow the plant, though in nothing like the former quantity. A vat has to be fed and watched daily once it is alive, which makes indigo closer to keeping an animal than to mixing a colour. It is settled while the cloth hangs in the air, and watching that happen is the reason to come.