The upper floors lean out a little over the road. Narai was a post town on the Nakasendō, and its townhouses are built in the deyari manner, with the first floor cantilevered forward on projecting beams. The row runs for roughly a kilometre, which takes about half an hour to walk end to end. The overhang is not decorative: it widens the sheltered space below and keeps rain and snow off the wall face, which in a valley this cold is a repair bill avoided rather than a style adopted.

Narai was designated an Important Preservation District in May 1978. Water basins fed by spring water stand at several points along the street, ladles still set out on them, and people walking through drink from them as a matter of course. Shrines and temples sit at the edges of the town, and shops selling Kiso lacquerware, made a few kilometres up the same valley, occupy a good number of the frontages along the way. The Chūō line station is immediately beside the post town, Shiojiri is about forty minutes away by car, and the winters here are cold even by the standards of Nagano.

A post town a kilometre long was on the large side for its period. The reason is topographic rather than commercial: in the Kiso valley the road cannot be widened, so a town that needed to grow could only grow lengthways, and the result is this single straight line of frontages with mountains close on both sides. Walking the full length, rather than turning back at the halfway point as most visitors do, is the quickest way to understand that the shape of Narai was decided by the width of the valley floor and not by anyone's plan for it.