Obokoso, Yakumo Onsen, Hokkaido –Two Different Springs and a Huge Golden Open-Air Bath in the Forest

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Few hot spring baths feel truly part of the landscape. In the mountains of southern Hokkaido, along the Namarikawa River, Obokoso is one of them.

The inn takes its name from Mt. Obokodake (1,167 m), which rises right behind it, and it has an unusual feature: the indoor bath and the open-air bath use two different spring sources.

Obokoso, Yakumo Onsen

Address	622 Namarikawa, Yakumo-cho, Futami-gun, Hokkaido 049-3128, Japan
Phone	+81-137-63-3123
Official Website	h-ffs.com/oboko
Day-use Bathing	Adults (junior high and up) ¥600 / Elementary school ¥300 / Age 6 and under free · 11:00–20:00
Check-in / Check-out	From 15:00 / By 10:00
Credit Cards	Accepted (JCB / Mastercard / VISA / AMEX / Diners Club and others)

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Getting There from Tokyo — Access Guide

Obokoso is remote, and the final stretch has no regular public transport. A rental car is by far the easiest way to get here. This guide assumes you start from Hakodate, the main gateway to southern Hokkaido.

Route	Tokyo → Hakodate (Shinkansen or flight) → rental car → Obokoso
Distance	Approx. 94 km from Hakodate (about 1.5–2 hours); 30 min by car from central Yakumo
JR Pass	✅ Hokkaido Shinkansen and JR limited express covered (taxis and rental cars not included)

A Secluded Inn in the Mountains

From Route 5, you follow a narrow road along the Namarikawa River into the mountains, and there is nothing around except forest. Mt. Obokodake stands right behind the inn, and its trailhead is close by, so hiking and soaking combine well here.

Left: The inn is more solidly built than “hidden hot spring” suggests. Right: The lobby feels more like a hotel, with a good souvenir corner.

The building looks and feels like a small hotel, so don’t expect a rustic cabin. Vending machines are plentiful, but food and shops are far away, so if you book a plan without meals, stock up in Yakumo first.

The Rooms

Toilet	En suite (in-room)
Refrigerator	Available
Air Conditioning	Available
Wi-Fi	Available
Television	Available
Towels & Yukata	Provided

My room was a compact six-mat tatami room — small, but with its own toilet and washbasin. Larger nine- and twelve-mat rooms are available if you need more space. The welcome sweet was a butter cookie from Hakodate.

The Hot Springs — Two Sources, Two Colors

Obokoso has gender-separated indoor and open-air baths. Each uses a different source, so you can compare two waters in one stay.

The Indoor Bath — Hot and Fresh

Left: A wide indoor tub framed by dramatic rocks. Right: Water pours in at a generous rate.

The indoor bath is a wide rock-lined tub, with water gushing from the spout at an impressive rate. The water is slightly cloudy and a pale yellow. I found it to be about 41°C, hot enough to warm you through but still easy to enter. It has a faint salty taste and a mineral, iron-like scent, and it delivered a pleasant tingle on the skin. Of the two baths, this one feels the fresher.

The Open-Air Bath — A Golden Giant ★

A door off the indoor bath leads down a screened path, and then the view opens up: a huge bath surrounded by forest, with the river right beside it. The scale is breathtaking. The color is just as striking — a deep golden brown I rarely see, concentrated especially near the overflow where the water runs toward the river.

Left: Nature on every side. Right: Touch the bottom and your hand comes away brown — the water is that concentrated.

Bubbles rise from the floor of the tub, so the spring seems to well up from below. The bath is much less hot than the indoor one, and it is so large that you can find cooler and warmer spots, so everyone can choose a comfortable temperature. The smell is also different from indoors: iron blended with a faint oily note, quite distinctive.

After dark, I had the bath entirely to myself, and sat in the quiet for a long while. It’s the kind of bath that stays in your memory.

Dining — Fresh Seafood from the Owner’s Fish Shop

The inn’s parent company is a fishmonger in Yakumo, and the seafood comes straight from the local catch. Scallop rice is the star.

Dinner

Left: Small appetizers to start. Right: Light mozuku seaweed and fresh sashimi.

Left: Crisp tempura. Right: Simmered flounder in a sweet soy-based sauce.

The sashimi was fresh, the tempura was crisp, and the simmered flounder had a sweet seasoning that went well with rice. A hot pot of Nagoya Cochin chicken (a premium Japanese chicken breed) came with udon noodles, perfect for soaking up the broth.

Left: Scallop rice with sweet corn. Right: The crispy okoge at the bottom.

The scallop rice was my favorite: scallop flavor soaked into every grain, with a pleasant sweetness from the corn. The okoge was addictive enough to eat on its own. If you stay here, don’t leave without trying it.

Breakfast

Left: A simple breakfast. Right: Miso soup with a giant scallop still in its shell.

Breakfast was simpler than dinner: steamed salmon, a silky hot spring egg, plenty of rice, and a scallop miso soup with an oversized shell-on scallop. For dessert, there was a jelly made from Soft Katsugen, a lactic drink sold only in Hokkaido. It tastes like a cross between Calpis and Yakult — unusual, and worth trying for the local color.

Final Thoughts

Obokoso combines a deeply colored, wide-open forest bath with a freshly flowing indoor bath and a seafood dinner worth the drive.

It feels like a genuine hidden hot spring while staying comfortable and practical. For many visitors, the open-air bath alone will justify the trip.

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