Hirakogi Onsen; Shiroyama Koshu Yokujo
Yamaga, Kumamoto, Japan
Illustration photo — not a verified picture of this exact spot.
- Location
- Yamaga, Kumamoto, Japan
- Water type
- thermal, sodium chloride
- Temperature
- 40 °C
- pH
- 7.3
Water profile
Thermicity
Sedative
LowHigh
Relaxing — deep, immediate muscle release.
Mineralisation
Restorative
LowHigh
Loaded with major ions — the essential minerals (Ca, Mg).
Buoyancy
Effortless float
LowHigh
Dense, salty water — you float without effort.
SodiumChloruresBrome
Hirakogi Onsen, including the Shiroyama Koshu Yokujo bath, is located in Yamaga, Kumamoto Prefecture. The thermal, sodium-chloride water reaches 40°C, pH 7.3. An indoor bath, an outdoor rotenburo bath and a sauna are offered.
Insider tip — 'Shiroyama Koshu Yokujo' (城山公衆浴場 — castle hill public bath) at Hirakogi Onsen in the Hirayama Onsen district of Yamaga. The 'castle hill public bath' references the historical Yamaga Castle site overlooking this traditional onsen neighborhood. Yamaga's community public baths (koshu yokujo) are among Kumamoto's most authentic — small, unpretentious, often with wooden fitting-rooms and simple tiled pools, serving generations of local families who walk from nearby homes with towel and soap in hand.
Nearby
Frequently asked questions
How hot is the water?
The water runs quite hot here, around 40 °C — a sedative water that brings immediate muscle release.
What type of water is found here?
This spot features thermal & sodium chloride water.
What is the best season to visit?
The most favourable period for this spot is: Toute l'année.