01 / Inaoi River
Tunnels cut into a cliff's flankcarried water up to the plateau.

The Sambongi plateau, once barren wild land, lies 30 m above the Oirase River, so water had to be brought from upstream. Two tunnel channels of about 4,460 m and a channel of about 6,147 m were dug, and the first water arrived in 1859. Nitobe Den, called the founder of the area's settlement, drove this man-made river.
- Two tunnel channels, about 4,460 m
- Channel, about 6,147 m
- First water, 1859
