Distance: 13.6 km
Elevation change: 561 metres
Highest point: 851 metres
Start: Shomaru Station (Seibu Chichibu Line)
Finish: Agano Station (Seibu Chichibu Line)
Map: Yama to Kogen Chizu 山と高原地図 ［No.22 奥武蔵・秩父 OKUMUSASHI·CHICHIBU］
Guide to Climbing Okumusashi’s Most Popular Mountain
Okumusashi is a general term for the mountainous area in the southwestern part of Saitama Prefecture. Thanks to its proximity to central Tokyo the area is a magnet for hikers and sightseers on weekends and holidays. Many mountains fall under the 1,000-metre ceiling making them climbable even in winter though lightweight crampons or microspikes should be carried. The most popular peak in this area is Mt. Izugatake suitable both for beginners as well as veteran hikers with a couple of expert routes to test your mettle. The hike described here is a standard course starting at Shomaru Station circling around to Agano Station. Mt. Izugatake rests along the “Okumusashi 105” a.k.a. Okumusashi Long Trail and from Mt. Ozo to Agano Station follows the Kanto Fureai no Michi.
From Ikebukuro take the Seibu Ikebukuro Line to Shomaru Station 正丸駅 changing once at Hanno (90 mins, 690 yen). Leave by the only exit and walk down the diagonal stairway which leads under the railway line. The hike is well signposted though there are unmarked trails veering off every which way so be sure to carry a map and GPS device. Continue walking up the bitumen which shadows a small stream adorned with momiji (Japanese maple). It takes 25 minutes to reach the trailhead proper. After a short distance you’ll come to a trail junction. Turn right in the direction of Kameiwa 亀岩 and Mt. Ozo 大蔵山 (720 m).
After reaching the upper ridgeline it steepens as you approach Mt. Gorinyama 五輪山 (770 m). Parts of the trail are poorly maintained with washed out wooden steps and plenty of loose gravely rocks and exposed tree roots to bring you unstuck. In the same vein as nearby Mt. Hiwada the compacted loamy clay path will be slippery as all hell in the rainy season so best avoided. Note the Otoko-zaka 男坂 trail is cordoned off due to rock-fall hazard so give the kusariba クサリ場 (chains) a miss and take the Onna-zaka 女坂 (now technically a detour) route for the final push up to Mt. Izugatake 伊豆ヶ岳 (851 m). As you approach the summit you can glimpse the shiny Seibu Dome roof and even Mt. Asama and Mt. Nantai on a clear day. Take care descending here as its steep and hard to get good traction.
After dropping down to a saddle prep yourself for another climb up to Komitake 古御岳 (890 m) before repeating the process as you make your way across to Mt. Takahatayama 高畑山 (695 m) the fifth mountain along the ridgeline. The next landmark to look out for is a forlorn looking transmission tower near Nakanosawa-no-atama 中ノ沢ノ頭 which can be side stepped if desired. Following this the trail drops down to Amamezasu Toge 天目指峠 before making a sustained climb back up again. If you can bear it a little longer a nice spot to take lunch is a shaded open clearing just after the small shrine atop of Mt. Atago but before Nenogongen 子の権現.
As you might have surmised from the gargantuan straw sandals, geta footwear and king-sized Nio statues the ancient Tenryuji Temple enshrines the ‘God of Legs’. From here it’s still another 5 km back to Agano Station 吾野駅. Walk downhill from the temple, when you hit the road look for a signpost on your right that begins a series of zigzags through cedar forest to the bitumen road at the valley bottom. As far as roadside walking goes the final stretch back to the station is rather picturesque. Just before the main highway swing right and follow this minor street for 1.5 km alongside the Koma River over the railway crossing and through a gloomy tunnel which runs beneath the Seibu Chibu Line.