Route name: Sekison-ryo (石尊稜)
Mountain: Yokodake (横岳) in the Yatsugatake range (八ヶ岳)
Map sheet: 33 [Yama-to-kougen-chizu (山と高原地図) series]
Time: 4-6 hours (in good conditions)
Length: 4 pitches + 4-500m simul-climbing
Difficulty: Grade 1+ alpine route / IV crux
The Sekison arête cuts steeply up the West face of Yokodake to the right of the Sanjahou-runze ice gully, and is the type of route that can shrink or grow in stature and experience according to the conditions of the day. In dry or consolidated conditions, it will be an easy romp up some of the most ‘big mountain’ terrain in the area. But in deep unconsolidated fresh snow it can provide the sort of day normally expected on a much bigger and wilder route. As such, don’t let the grade lull you into under-estimating it; check the weather and snow conditions in the week prior to your ascent, and plan accordingly.
With rock pitches at the bottom and top, the middle section is a stunning snow arête that snakes up through the wide bowl of the upper West face, providing views across the whole sweep of the face to both left and right. Don’t forget your camera, because in snowy conditions this route is surely one of the most photogenic in the area!
If travelling from Tokyo, take a Super Azusa Limited Express train from Shinjuku to Chino (approx. 2.5 hours). Outside the JR station at Chino take a bus to Minotoguchi (美濃戸口, approx. 45 minutes). This is the gateway to the Akadake-kōsen side of Yatsugatake. From the carpark start hiking up the trail that is signposted to Akadake. The walk-in takes up to 3 hours by map time. It is split into 3 stages. The first hour brings you past a series of buildings and on a little further to a hut with a water source, which makes a good resting point for 5 minutes. The trail splits here, with the right fork going up Minami-sawa (南沢) to the Gyouja-goya hut (行者小屋). This is the quickest approach if you are planning a single day round-trip ascent. If you are planning on staying in the Akadake-kōsen hut, you need to take the left fork up Kita-sawa (北沢). The next hour follows the rough dirt road until it finishes at a bridge across the sawa. From the other side the path narrows and meanders alongside the sawa for another hour or so until you reach the hut at Akadake-kōsen. This hut and its campground serve as basecamp for all the routes in the area, as well as for the popular Ice Candy artificial ice wall.
As you exit the Akadake-kōsen hut by the front door turn right and follow the trail to the end of the hut and then up through the forest. Cross the bridge and keep going until you reach the foot of the first of the zigzags that head up to the Nakayama ridge. This is the entry point for both the Sanjahou-runze and the Sekison arête.
Enter the sawa and keep going for several hundred metres, slowly gaining height and keeping right at any forks you come to. Eventually you will arrive at the foot of the arête, marked by a piece of tape on a branch. In deep snow conditions you may find it easier to continue for another hundred metres or so and then strike up left to gain the arête slightly higher.
Once on the arête, continue up through easy but exposed terrain until you reach the foot of the first rock step. There is a good tree to belay from about 6m below the rock.
Although this slabby rock step only gets grade III/IV on topos, it is quite simply nasty. If buried it will require laborious cleaning of snow at every move, just to reveal what scant hand and foot holds are available. There are several ways it can be tackled, and some say that left is easier. We went right, and found it deeply unpleasant.
After about 50m you can belay on trees below the top.
From here there follows about 200m of steep and exposed snow climbing up the magnificent lower arête, protected by slings on trees wherever possible, until you reach the top of a sort of pinnacle. In good conditions it can be simul-climbed, but be prepared to pitch it if necessary.
From here make a short down-climb and cross a knife-edge section of about 20m, and then simul-climb up the arête for another 200m to the bottom of the second rock step. This section of arête goes through some of the most picturesque scenery of the day, and has the atmosphere of a much bigger and more serious climb.
There is an in-situ anchor at the bottom of the rock step. Climb up the initial chimney then make steep moves out to the right on the arête. Continue up until you reach the top where the route continues to the right through a rock cleft.
Climb another pitch through this cleft and up into the gully above until your rope runs out. From there you will just have another 10-20m to the top. Again, depending on conditions, you could consider simul-climbing this upper section through the gully.
As the angle eases you will arrive at the top just short of the main hiking trail from Yokodake. The views from up here are absolutely stunning!
Once at the hiking trail, you have several options:
(i) The quickest way to get back down is to head south in the direction of Akadake and descend the hiking trail down the Jizo-one ridge to the Gyouja-goya hut.
(ii) You could head north to traverse Mt Yoko over to Mt Io, and then descend from there back to the Akadake-kōsen hut.
(iii) If you wish to summit the highest peak in the Yatsugatake range, simply continue southwards on the trail and up to the top of 2899m Mt Aka. Continue over the summit and down to the Bunzaburo ridge trail and follow it all the way down to the Gyouja-goya hut.
Like the famous phenomenological images where different people will either see a duck or a rabbit, or a young woman versus an old lady, this classic route will doubtless engender differing reports. Those who catch it in consolidated conditions will say it’s easy. But those who find it under deep fresh untracked snow will hold a far greater respect for the sort of experience it can provide. For my partner and I it was extremely memorable, and I recommend it unreservedly. Take plenty of slings for protection, and don’t forget your camera.
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