The “Araigoshi” are channels for rainwater to flow through the path. The channels, which are lined with stone, are cut every 5 meters to enable the water to flow down the mountain to the valley.

Since there is a lot of rain in the area, the stones are laid out in a way that allows for natural drainage. This isn’t unique to Matsumoto-toge Pass but can be seen in all the ancient roads of the Iseji Route. Due to the maintenance of the roads, you can see the drainage channels now, but in the past, they weren’t noticeable because they were hidden in the earth.

The stones are packed tightly and are sturdy enough to not be damaged by the rain, but the Araigoshi channels are an additional measure to protect the stones from water damage.