Okunoyu

黒川温泉 奥の湯くろかわおんせん おくのゆ

Lodging
Kyushu & Okinawa·Kumamoto

Day Use

Yes
08:30–20:00

There are shortened days (from 15:00) and weekends.

Bathing & Water

Outdoor BathYes

Open-air outdoor bath

Indoor BathYes

Enclosed indoor bathing area

SaunaYes

Dry heat sauna room

Cold BathYes

Cold water plunge bath, typically used after sauna

OnsenYes

Uses natural hot spring water

Capabilities

Private BathYes

Private bath available for day-use visitors or hotel guests to reserve

Room OnsenYes

Private onsen bath in guest rooms, for overnight guests only

Mixed BathingYes

Shared bathing area for all genders

Policies & Services

DiningYes

Restaurant or dining open to visitors (not just hotel meal plans)

WashingYes

Shower, wash stations, soap and shampoo provided

ParkingYes

On-site or nearby parking available

奥の湯

Okunoyu Spring

Operated by · 黒川温泉 旅館 奥の湯

Simple
Color
nearly colorless and clear
Taste
faint metallic taste
Odor
hydrogen sulfide odor

Sodium Sulfate-Chloride spring

Hot source · 73°CHigh silica
Composition fingerprint0.5 g/kg dissolved · Hypotonic
Na⁺57
Ca²⁺16
K⁺16
SO₄²⁻67
Cl⁻24
CationsAnions
Sodium Na⁺
salt's cation — pairs with chloride to make the water salty.
Sulfate SO₄²⁻
"gypsum / Glauber's salt" — vessels and wound healing.
Known good for
  • Aches & jointsstiff shoulders
  • Smooth skindry, rough skin
  • Recoveryfatigue, stress

A gentle simple thermal spring in the hypotonic, neutral, high-temperature class, emerging at 73.1 °C — among Japan's hotter natural sources. Lightly mineralized and easy on the body, it is nonetheless rich in metasilicic acid, placing it in Japan's beauty-water family: the silica leaves a thin moisturizing film that makes skin feel smoother. The water is nearly colorless and clear, carrying a faint note of hydrogen sulfide and a whisper of metallic taste from its trace iron — real character for a spring classified as simple.

Analyzed Dec 6, 2022

Explore the water

Views

River
Forest
Waterfall

Highlights

Cave Bath

Programs

Loading map…

5.0

1 review

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Sergey M
1 year ago· edited

15. Okunoyu, Kurokawa Onsen ★★★ Visited on a day trip. This ryokan with a mixed-gender rotenburo is located east of the central area of Kurokawa. Day-use is usually available from 08:30 to 20:00 and from 15:30 to 20:00, sometimes only on certain weekdays. It is part of the Kurokawa tag. Day users are allowed access to the main mixed-gender outdoor bath and the adjacent indoor single-gender bath. Guests staying overnight have access to another indoor bath and three private baths. The ryokan provides its own branded towels. 1. Large mixed-gender outdoor bath area. Amazing view of the forest, river, and waterfall. Due to the elongated architecture of the baths, the view of nature is wide and even more impressive. 1.1. Large main stone bath. The water is clear with a slightly cloudy white-green tint. Temperature about 42°C. 1.2. Cave bath with a view. Water temperature about 39°C. 1.3. Small distant stone bath with a view of the waterfall. The water is clear with a slightly cloudy white-green tint. Temperature about 39°C. 1.4. Sauna. 1.5. Cold bath. 2. Indoor single-gender bath. The water is clear with a slightly cloudy tint, temperature about 42°C. Very comfortable to breathe. A very impressive outdoor bath area. If you are not bothered by the mixed-gender bath format, this place is a must-visit.

Onsen Oni

Last updated July 15, 2026