Agematsu was well-known in the Edo period for being the location of the office for the forest commissioners of the Kiso valley. Rules regarding access to the valuable timber resources of the valley were very strict, and punishments were severe even for those caught trying to glean a little firewood without permission. The town was quite large in 1841, with a population of just under fifteen hundred. Agematsu also had the largest number of inns (35) of any town in the Kiso valley. It remains an important service town in the valley today, with many modern shops clustered around the station. Unlike neighboring Kiso-Fukushima, however, express trains do not stop here and so the potential for further growth is limited.
Leaving the town the old highway becomes lost under the line of the railway and the modern road. This has been the typical pattern for most of the journey along the Kiso valley so far, mainly because the valley is too narrow for multiple routes. The scenery is attractive, however, especially if the weather is clear enough to allow a glimpse of Mount Ontake; considered one of the most sacred mountains in Japan.
Further on, there are occasional traces of the old highway which can be followed, but each of them runs into a dead-end or into some construction on the hillside. Attempts to follow the original route instead of the modern highway lead mainly to frustration. There are several truck stops to offer refreshment, however, before Kiso-Fukushima is reached, some six miles after Agematsu.