Kami city gives the viewing period at Befu-kyo as early to late November. It also publishes something more useful: a table of the peak week for each of the last ten years. Six of those ten peaked in the first third of the month and four in the middle. None peaked late.

That is worth knowing before you book. The published band runs to the end of November because some years run long, but the record says the first half is where the odds sit. Very few local authorities put both the band and the history on the same page, and the pairing tells you more than either would alone.

The gorge is at the headwaters of the Monobe river, inside the Tsurugisan quasi-national park, at around five to six hundred metres. The city also lists what grows here — shide, omomiji, yamamomiji, ivy, beech, with larch and ginkgo mixed in — which is why the colour arrives in stages rather than all at once.

Getting in takes some doing. A JR bus from Tosa-Yamada station towards Birafu takes twenty minutes, and you change there for the last stretch. By car the road follows the river up and parking at the gorge is free. There is a rest house and a lawn area near the bridge, and not a great deal else, which is much of the appeal.