The rock gets your attention before the leaves do. Oboke sits on the middle reaches of the Yoshino river, with thousand-metre ridges on both banks, and its stone is sandy schist — metamorphosed sandstone whose weathered surface turns pale blue-grey and green. The autumn colour, at its best in mid to late November, lands on top of that cool ground. Red on grey does not dull. It carries.

The walls themselves are worth reading. Thick beds of rock folded into waves, cracked, then cut away along the cracks: that sequence made the gorge, and the banding is legible at eye level and far above it. The colour comes out of the gaps between the bands, as though the mountain were showing its seams once a year.

Sightseeing boats work the river through the gorge. From water level the rock stands directly overhead, and the arrangement you had on foot is reversed — you look up at what you looked across at. Half an hour on the water rearranges the whole place.

Oboke station on the JR Dosan line sits beside the gorge, and the river is visible from the train, so the season starts before you arrive and continues out the window after you leave. Downstream the gorge narrows into Koboke, which fewer people bother with. Bother.