Shiki no Yu Onsen
Kumagaya, Saitama, Japan
- Location
- Kumagaya, Saitama, Japan
- Water type
- sodium chloride, thermal
- 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
Shiki no Yu Onsen, in Kumagaya, Saitama Prefecture, offers sodium-chloride thermal water at 40°C, with an indoor bath, an outdoor rotenburo and a sauna.
Insider tip — Kumagaya holds the all-time temperature record for Japan: 41.1°C recorded in July 2018, surpassing the previous record set in Tajimi. The city's infamous summer heat earned it the nickname 'Japan's hottest city.' The Kumagaya Uchiwa Festival (fan festival, mid-July) celebrates traditional ways of cooling down — ironic for a city this hot. Shiki no Yu (Four Seasons Bath) offers thermal soaking in all four seasons, though arriving in summer means stepping from 41°C outdoor heat into 40°C bath water: a uniquely Kumagaya sensory experience.
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 sodium chloride & thermal water.
What is the best season to visit?
The most favourable period for this spot is: Toute l'année.