The Kurobe and Unazuki tourism bureau gives the usual season here as late October to late November. The reason for the length is vertical. The gorge drops several hundred metres from rim to river, and the colour takes three weeks to a month to travel from the top down to the water.

The bureau publishes it station by station. Keyakidaira and Kanetsuri, the two highest stops, run late October into the first days of November. Kuronagi and Lake Unazuki follow in the first half of November. Unazuki itself, at the bottom, starts in early November and holds on longest. Twenty kilometres of track connects them, laid originally to build the hydroelectric plants upstream rather than to carry anyone on holiday.

The trains reflect that history. The cheapest carriages have no windows, only open sides and a roof. They are the ones worth taking, and the ones that will make you cold. October morning averages are about fifteen degrees at Unazuki and twelve at Keyakidaira, and it drops further inside the tunnels, of which there are many. A proper coat, not a jumper.

Two things to check before travelling. Services along the line have been running on a reduced pattern since the earthquake, so confirm how far up the track is open on the day you want to go. The hot spring facilities along the route close for the year in early November, before the colour finishes at the bottom of the valley, so a late trip may give you the maples without the bath.