The Nagasaki prefectural tourism federation gives the usual peak at Nita Pass as late October to mid-November. The pass sits in the middle of the Shimabara peninsula, in the mountains of Unzen, and it is the point from which most people look at the range rather than a place you pass through on the way somewhere else.

A ropeway runs from the pass up the slope. From the car and from the upper station the view opens onto Heisei-shinzan, the lava dome that grew during the eruptions at the start of the 1990s and is now the highest point in the prefecture. The second observation deck brings you closer to it than anywhere else you can reach on foot, close enough to read the texture of the rock.

The road up is a loop and it runs one way. That matters more than it sounds: once you are on it you complete the circuit, and on busy autumn weekends the queue on that single direction of travel is the main cost of the day. Going early is the usual advice.

Unzen changes character through the year. Miyama-kirishima azalea covers the slopes in spring, the green thickens through summer, and in the cold months rime ice forms on the trees. The turning of the leaves is the short interval between them, and it works down the mountain: by the time the pass is finished the hot spring town below has started. Unzen Onsen is a few minutes' drive down.