In these three-storey houses, the upper two floors belonged to the silkworms. Akaiwa is built on stacked stone terraces cut into a slope, with three-storey farmhouses standing above one another on the steps. The upper floors were rearing rooms, fitted with runs of windows in a line to move air through, and that row of openings is the first thing you notice from below — a farmhouse elevation that looks unexpectedly industrial.

Silkworms are sensitive to both temperature and humidity, so they had to be kept apart from the living quarters and high in the building, where heat and damp could escape. Akaiwa was designated an Important Preservation District in July 2006 and remains a settlement of a few dozen households in a mountain valley. Nakanojō's town centre is about forty minutes away by car, the winters are properly cold, and because the village is on a slope, how much sun a house receives depends entirely on where it stands in the sequence.

Sericulture meant building a factory inside a house, and then living in the part that was left over. Since the family's life and the rearing of the worms had to occupy the same structure, the answer was to add floors rather than to build separately, and that decision is why a mountain village ends up with a row of three-storey buildings where two would be usual. The windows record the rest of it. A line of openings at that height, in a place with this climate, is a plain statement about what was going on inside the building, legible from the road below without anybody needing to explain it to you.