Mt Kinpu (金峰山 2595m) and Mt Mizugaki (瑞牆山 2230m) are two of the high peaks of the Chichibu Tama Kai National Park, and both have the distinction of featuring on Fukada Kyuya's list of the 100 finest mountains of Japan (Nihon Hyakumeizan).
They sit across the valley from the South Alps, slightly southeast of Yatsugatake and northwest of the Daibosatsu ridgeline. Granite towers, blocks and obelisks protrude from the summits of both mountains, and just a couple of hours walk from both of them lies the rock-climbers paradise of Ogawayama (小川山), which many people argue is the best rock-climbing spot in Japan.
The nearest station is Nirasaki (韮崎), on the Chuō Line, and from there a bus will bring you to the trailhead at Mizugakisansō. You should be aware that the last bus back to Nirasaki departs from here at 3pm, and a taxi ride back will cost about 11000 yen, so take care not to miss that bus!
A short way up the trail, about 50mins of map time, there is a hut at the point where the trail forks. Go left and you will descend a short slope to a river crossing, and from there on the trail rises steeply to the top of Mt Mizugaki. Take the right fork, however, and the trail will take you up the long ridgeline to the summit of Mt Kinpu. Many hikers choose to stay the night at this hut and split their hike into 2 days, with one summit on each day, thus ensuring that they can get the bus out in time.
If you have plenty of time available you can continue along the ridge from Mt Kinpu to hit Mt Kobushi (甲武信岳 2475m), another of the hyaku meizan.
Alternatively if you're fit and can move fast and light you could do what we did this November, and go for it in a single day. The trails are not ideally suited to running, but as we discovered, it is perfectly possible and even a lot of fun! Although we were denied the clear skies we were hoping for, it was obvious that on a blue sky day the views from both of these summits would be outstanding. If you're looking to tag two big mountains in a day then this is a fine route to take.
Here's a little video we shot of the run: