Kawarayu Onsen

Nakanojo, Gunma, Japan

Location: Nakanojo, Gunma, Japan
Water type: sulfurous
Temperature: 44 °C
pH: 6.5

Water profile

Thermicity

Sedative

44 °C

LowHigh

Relaxing — deep, immediate muscle release.

Mineralisation

Bio-active

LowHigh

Rich in active gases or metals — a strong mineral character.

Buoyancy

Standard buoyancy

LowHigh

Soft water — natural, classic buoyancy.

SoufreSulfuresSulfates

Kawarayu Onsen in Naganohara Town, Agatsuma District, Gunma Prefecture is one of several hot spring destinations in Japan honored with its own dedicated railway station — Kawarayu Onsen Station on the JR Agatsuma Line — a recognition of the spring's cultural and recreational significance within Gunma's extraordinarily thermal-rich mountain landscape. The sulfate-rich thermal waters of Kawarayu Onsen are traditionally associated with relaxation and recovery, reflecting the long tradition of mountain onsen bathing that has defined Gunma's volcanic hot spring culture for centuries. The combination of direct rail access and the distinctive quality of its sulfate mineral water makes Kawarayu Onsen an accessible and valued destination for visitors traveling into Gunma's volcanic interior without personal transport.

Insider tip — Kawarayu Onsen lies along the Agatsuma River in Gunma's volcanic highland interior, historically celebrated as a restorative spring during the Warring States period. The sulfate-rich water at 44°C is known by the traditional designation of kirikizu no yu or wound-soothing water. The small onsen hamlet retains its Meiji-era wooden bathhouse architecture largely intact, creating an authentic historical atmosphere. The remote valley setting means stars are brilliantly visible on clear nights from the riverside outdoor baths.

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