This is the trailhead to enter the Ancient Tosando trail, coming from the Nakasendo in Nakatsugawa, Gifu prefecture.
The Tosando (east mountain road) is Japan's oldest national road. It was established 1,300 years ago by the imperial court in Kyoto, during the Heain period. It played a key role in the invasion of the emishi territories in north-east Japan.
While the Tosando has fallen into disuse and is only preserved as a hiking trail between the Nakasendo (Kiso Valley) and the Sanshu Kaido (Ina Valley). Its historic counterpart, the Tokaido (east sea road) today is Japan's major transport artery.
There is a picnic shelter and a restroom close to the trailhead. There are also several ruins of old natural cold storages (muro). These were dug into the mountain and used natural cool winds to store grains and food for longer periods. You can still feel to cold around them. From here it is roughly a 90 minutes hike to Misaka-toge Pass and Southern Nagano.