Hiking from the Chuo Line 中央線
I’d been through Otsuki so many times, on my way to either the Mt Fuji Five lakes area, or Kofu city, and each time I saw this rocky hill jutting up behind the city. Since it’s not a very big mountain, I did it as a morning hike, returning to Tokyo around noon. At the moment, two out of the three hiking trails are closed, these closures predate typhoon Hagibis, but it’s still possible to hike up via the back of the mountain. After reaching the highest point, it’s possible to continue along the ridge westwards for another hour, and finally walk back to Otsuki station forming a loop; since it’s a popular hike, there are warning signs and maps about this right outside the station, and along the approach to the trailhead.
Autumn colours still on display in December
I used the convenient and comfortable Chuo line limited express to get to Otsuki station, only one hour from Shinjuku. It took me another hour to reach the start of the trail – Hatagura tozanguchi 畑倉登山口, just opposite a driving school. Although I had to walk on the road, there were good views of Katsura river (which later becomes Sagami river), Mt Momokura and Mt Gongen. The crisp autumn weather made all the surrounding mountains clearly visible. After crossing the river, I turned around, and I saw the snowy top of Mt Fuji rising behind Otsuki city.
The hike follows the ridge from right to left
From the start of the hiking path, it took me just half an hour to reach the top of Mt Iwadono 岩殿山. It used to be the site of a castle, Iwadonojo 岩殿城 but there isn’t much left now. I was rewarded with an amazing aerial view of Otsuki town with Mt Fuji in the background. On the left, were the Doshi mountains, and on the right, were the Misaka Mountains. I was standing on top of the rocky face of the mountain, with nothing but a low fence and some bushes separating me from a hundred meter drop. My arrival at the top coincided with that of a rather large group, and I was asked to take their photo. One of the group members very kindly offered me some sweets in exchange. After they had moved on, I enjoyed an early lunch.
Spectacular view from the top of Mt Iwadono
Fortunately, my hike wasn’t over yet. From the summit, I continued along the ridge, first heading down for a short while before climbing again. I soon reached a fork where I had 2 choices – the forest path or the rock climbing path. Unfortunately, the group I had encountered at the summit, were now busy making their way up the rock climbing path – there was no way to get around them. Since I was on a schedule, I took the less exciting forest option. However, the paths merged soon after, and I found myself ahead of the large group, so in the end it was a blessing in disguise.
Last good view of Mt Fuji
I had some more excellent views of the valley below, and Mt Fuji, while hiking along a narrow, rocky ridge. I had imagined that this would be an easy hike, but it turned out to be quite exciting. It took me less than an hour to reach the top of the next summit, Mt Tenjin 天神山, surrounded by trees. A few minutes later, I reached an impressive rocky face called Chigo-otoshi 稚児落とし. The hiking path took me above it, where I had some more great views of the area. Standing on top of the highest boulder, I took in the last views of today’s hike. From there, the path descended steeply through forest to Asari 浅利 at the bottom of the valley, and it was another 30-minute walk along the road back to Otsuki station, which I reached just before noon, nearly four hours after setting out. I was glad to find a mountain that hadn’t been too affected by last year’s powerful typhoons. Apart from one fallen tree, the trail and the surrounding forest seemed in good shape. Hopefully the other trails will reopen sometime in the future.
Chigo-otoshi at the end of the hike – no safety fence here!
Hiking Around Tokyo 
There was a small planetarium on the mountain when I lived at the base of the mountain in the 90’s.
Wow really? was that at the highest point? did you ever use it?