A rice terrace looks like scenery. It is really a water machine.

Every field on a Japanese mountainside has to be flooded to a set depth at a set time of year, and then drained again. There is no pump. The water comes from a stream or spring high on the slope and reaches each field because somebody, generations ago, worked out the line it had to follow - and because somebody today still opens and closes the gates.

This day is about that system, walked from the top down.

We start at the intake, where the channel leaves the stream. From there you follow it on foot: along the contour, around the shoulders of the hill, over whatever the builders had to do where the ground dropped away, and into the head of the terrace. Then you watch what happens at each level - how a field fills, where the outlet sits, why it is never in the same corner as the inlet, and how the water leaving one field becomes the water for the next.

The stone walls are the other half of it. They are built dry, without mortar, so water can move through them instead of pushing them over. Your guide will show you a wall in good order and a wall that is failing, side by side. After that you will not be able to stop noticing the difference.

You will also hear the part nobody puts on a poster: who decides the order in which fields get water in a dry year, how that has been settled in this village for a very long time, and what happens now that there are fewer people left to argue about it.

Walking is about 3 to 4 hours, mostly level along the channels, with uneven ground and short climbs between levels. This is not farm labour. You are not planting or cutting. You are learning to read a landscape that most visitors only photograph.

We finish at the village hot spring, which is the right way to end a day spent beside cold running water.

If the channels are dry, or the route is unsafe on your date because of snow, heavy rain or repair work, your driver-guide takes you to a similar place nearby instead. The tour price does not change. We can run the woodland and hot spring day instead, but only if you prefer that.

Your private van, driver-guide and the whole day are yours alone. No other customers join. Pickup and drop-off anywhere in Tokyo's 23 wards, and the order of the day is yours to change.