The Okuizumo tourism association gives the usual colour here as late October to mid-November. Oni-no-Shitaburui is a V-shaped gorge about two kilometres long, cut by the Omaki river — a tributary of the Hii — through a bed of biotite granite. Sheer walls on both sides, boulders stacked in the bed, and potholes worn into the rock by water turning stones for a very long time. It is designated both a place of scenic beauty and a natural monument.

The name comes from a story rather than a description. A goddess called Tamahi-hime is said to have lived here, and a wani who loved her came up the river night after night until she blocked it with boulders. Wani ga shitatta, the wani yearned, is held to have worn down over centuries into Oni-no-Shitaburui. There are other versions.

The practical change came in 2013, when a suspension bridge and a new walkway opened along the whole gorge. The bridge is forty-five metres high and a hundred and sixty long, and the route from the Une car park to the Shimotakao car park is passable by wheelchair from end to end — unusual for a gorge of this kind.

It is two kilometres between the two car parks, about an hour each way unhurried. Entry is free and there is no closed day, though the town does not clear the paths in winter and asks visitors to stay away once snow lies.