I'd been to Kyoto many times before but never had made it out to Takao, so I scheduled a day to take in the Takao temples of Kozanji, Saimyoji, and Jingoji and then hike to the Hozu River. The 3 temples took a lot more time than expected as I took my time enjoying the solitude as very few people were anywhere on a Friday morning in January. Coming down from Jingoji, I began following the "trail" that followed the river downstream. It was more of a road in width, and even had tire tracks in places. For the entire walk down to Kiyotaki, I met no one, and only saw some wet boot prints going the same direction that I never caught up with.
The trail followed the crystal clear river with little climbing or dropping following well above the height of the water. There were many repetitive signs in Japanese stating there was a dam upstream and the water level could change quickly as well as trail markers indicating it was a "Kyoto Trail." About halfway to Kiyotaki a bridge crossed the stream and there was an area with a few picnic tables and a deteriorating building. Past this, just above the village of Kiyotaki, the trail turned away from the river as the walls got too steep for a trail, and followed a side stream uphill for a couple of hundred meters. Another sign pointed uphill to the left for the main trail as another trail continued following the side stream. At the top of this hill, the trail met a narrow paved road, where I saw my first person - a mailman on his red Honda scooter/bike.
I followed this road well above the Kiyotaki River, looking down for another trail in case I missed it, but never saw another, so the road into the village of Kiyotake was the trail. Here, a side trail to the east would take you to a waterfall with a torii and other shrine markings, while the main trail went down some steps to the right on the far side of the first bridge. The last bridge in the village is pedestrian only and leads to the trail from Kiyotaki to the Hozu River. This becomes a real trail, narrow and a rocky scramble in places, but still not difficult. It was along this section that I met the only other hiker who was going the opposite direction just to see the waterfalls.
The river was still crystal clear but was gathering in volume below the village. Remnants of high water flotsam occasionally were piled up at low places on the trail. This lower part of the trail was the nicest section in my opinion. Eventually, a last bridge led to the trail going uphill away from the river to meet a paved road. Here, a right turn overlooking the last of the Kiyotaki River, led through a short tunnel to an overview of the Hozu River (Hozugawa). From here, the first place of interest was where a bridge led across the Hozugawa to a tram station. To get to the JR Hozukyo Station, you had to continue uphill on the paved road for a km or so and then go down a km or so. At the top, you could see across the river to the JR station. The station was unmanned with only a drink vending machine, but was located on a bridge across the river giving good views. The local trains stopped at the western end of the bridge even though the waiting shelter was in the middle. The ride back to JR Kyoto was much faster than the bus out.