As you can see, "along the river" soon changes to "up the river." Technical note: this is not the main road (route 370) but the former logging road (route 371), more roundabout but with spectacular scenery. It's not a huge climb; Koya is only at around 850 meters elevation. But if you really want to cheat, there's a tiny train that goes up from Hashimoto to Gokurakubashi not far from the central temple area.

One look at this photo and any Japanese person would know immediately what season I made this trip in - the autumn higan-bana flowers are a dead giveaway. Even the name alone would be a giveaway: it means "autumnal equinox flower" (the English name, cluster-amaryllis, is a lot less enlightening... though they definitely come in clusters. Higan-bana are ubiquitous in late September, and one of the the preeminent symbols of the season - like the cicada in summer, or the wooden clappers of old in the winter. Maybe not so old - as recently as 20 or 30 years ago, people used to wander the streets even in the Tokyo area in the evening banging wooden clappers together to warn people to put out their heating fires (fire is a particular problem in winter when the air is so dry).