Ichinosawa Ōtaki (一ノ沢大滝) ice-climbing

Route Name:  Ichinosawa Ōtaki (一ノ沢大滝)

Area:  Ōmukawa (大武川) river drainage

Map sheet:  41 [Yama-to-kougen-chizu (山と高原地図) series]

Time:  1-2 days

Grade:  WI4 / Overall grade 4+ alpine route

The Ichinosawa Ōtaki is a real gem, a huge icefall hidden deep in the Ōmukawa drainage at the northern end of the South Alps between Mt Kaikoma and the Houousanzan range. Rising some 170 metres from a narrow, secluded gorge, the route offers sustained, engaging ice rather than a single dramatic crux, with difficulties that are modest on paper but serious in context.

What distinguishes Ichinosawa Ōtaki is not steepness alone, but scale, remoteness, and commitment. The long, complex approach, the exposed descent into the valley, and the sheer length of the climb combine to create an outing that feels unmistakably alpine. Retreat or self-rescue would be extremely difficult from here in the event of an accident. When conditions align, the result is a climb of unusual stature in Japan.

Getting there:

If travelling by car from Tokyo (東京), take the Chuō Expressway to Nirasaki IC (韮崎) and then exit onto route 27 heading west to join route 20 (甲州街道). Continue along route 20 until the turn-off for the Ōmukawa Forest Road (大武川林道).

Turn toward Ōmukawa and follow the forest road upstream past the Shinosawaotaki camping ground (篠沢大滝キャンプ場). Drive as far as winter conditions and snow clearance allow, typically to the gate / parking area used as the trailhead.

Description:

THE APPROACH

Part of what makes the Ichinosawa Ōtaki such a serious outing is this approach. It takes approximately 5-6 hours from the gate to the foot of the Ōtaki, and most of that time is spent on steep and complex terrain. For this reason, most parties choose to carry in camping gear and do it over two days, walking back out on day two in daylight. But it can be done in a long day by a fit and competent team.

From the gate you need to walk up the rindou for around half an hour until it crosses a bridge over the Ōmukawa river. After this bridge you need to head up steep slopes to gain the ridgeline above. There are multiple spurs and minor ridges coming down off this ridgeline, which is fine on the way up, but could cause problems on the way back down if in the dark.

Once you hit the ridgeline, just continue up relentlessly on frozen soil and leaves through the forest. It is steep and exposed in places, and chain spikes are recommended. After several hours of this you will reach the 1393m ‘summit’ of this ridgeline, from where you may glimpse the Ōtaki in the distance.

Now you need to descend into Ichinosawa, and most teams find this next hour rather unpleasant. It is steep and exposed, with no trail to speak of. In poor conditions you may need to rappel from trees.

When you arrive at the bottom, turn right and start heading carefully up the Ichinosawa stream, over boulders and frozen ice steps at WI2-3.

At one point you will arrive at a 50m icefall named the ‘lower Ōtaki’ (下の大滝). If this is not formed well enough to climb it, bypass it by heading steeply up the slopes on the right bank, traversing past it and then descending back into the sawa.

After about an hour or so of this you will eventually arrive at the foot of the enormous Ōtaki.

THE CLIMB

The Ōtaki is approximately 170m tall, stunningly beautiful, and is climbed in four pitches if you have 50m double ropes. Mentally it can be split into three sections, with the middle part being the steepest and most challenging.

Pitch 1: Climb the lower wall at around WI4. This first pitch is rather chandeliery and thin in places. The first 30m is steep, and then it eases off slightly to continue up better ice to belay on a narrow terrace under a rock wall on the right edge. (45m WI4)

Pitch 2: Continue up on the right side of the icefall until things steepen to a sustained 80 degrees, and belay on screws at the end of your rope. (40m WI4+)

Pitch 3: Continue steeply for around 30m, before things begin to ease off slightly. (40m WI4+)

Pitch 4: Continue up slab ice and steeper steps until you arrive at the top. (50m WI3-3+)

From the top of the Ōtaki, descent can be made in 4 rappels on double ropes from v-threads (abalakovs).

Once safely back down at the foot of the icefall, you now need to reverse the initial hour back down the sawa, making short rappels down various ice steps where needed.

Once you reach the point you entered the sawa from, you now need to ascend the steep slopes back up to point 1393m on the ridgeline. From there you must reverse your approach route back down the ridgeline to the forest rindou. This is where things can get tricky in the dark. With many ridges dropping down from this main ridgeline, it can be very hard by headtorch to locate the correct ridge without GPS. Keep a rope near the top of your pack because you will most likely have to resort to rappelling off trees at some point, depending on conditions and which ridge you end up descending.

Eventually you will hit the rindou, and a more relaxed walk back across the bridge and out to the gate and your car.

Overall:

One of the great prizes of Japanese winter climbing, and a full-on mountain day defined by endurance, judgement, and atmosphere. Take double ropes, around 12-14 ice screws, and consider chain spikes for the approach and walk back out. Most importantly, be sure of your fitness and preparation and understand the scale of the day you are in for. Despite the modest altitude, this is a far more off-piste ‘alpine’ day than anything on the nearby Yatsugatake range, and will provide a proportional sense of accomplishment.