KoyaruOnsenMorinoYu

A tranquil therapeutic retreat surrounded by forest

Chiba Yachimata City

Koyaru Onsen Mori no Yu is a day-use hot spring facility in the satoyama of Yachimata, Chiba Prefecture, with the atmosphere of a luxury inn. The iodide-sodium-chloride strong saline spring gushes up from 1,700 m underground, with an amber color, excellent heat-retaining properties, and a silky feel that blends gently into the skin. The men's sauna is set at a high temperature of nearly 100°C, offering a compact yet powerfully intense heat. A standout feature is the cold plunge bath made with well water. With a depth of 110 cm, it envelops the entire body and promises a refreshing cool-down. On the women's side, there is also a gentle mist sauna. With free detox water and well-appointed relaxation areas, it is a place where you can spend an entire day at leisure with attentive service throughout.

Hot Spring & Bath Information

Koyaru Onsen

TypeNatural Hot Spring

An amber-colored saline spring that gushes up from 1,700 m underground. Its rich mineral content and strong heat-retaining and moisturizing effects are its defining features, leaving the skin feeling enveloped. In the outdoor bath area, there are a variety of tubs such as Takami no Yu and Dokutsu no Yu, allowing you to fully enjoy a famous hot spring while taking in the natural beauty of the satoyama. After bathing, your body stays warm for a long time, gently relieving fatigue from deep within.

Sauna

High-Temperature Sauna

100°C

Sauna TypeDry Sauna

Stove TypeInfrared Heater

Capacity8people

Men's

A compact but authentic dry sauna installed in the men's bath. The room temperature reaches nearly 100°C, and the dry, powerful heat quickly triggers a full sweat. In the quiet interior, it is a space where you can face the heat at your own pace. Right outside the sauna room is a deep cold plunge bath, and the flow of movement has been perfectly planned.

Mist Sauna

40°C

Sauna TypeMist Sauna

Capacity6people

Women's

A sauna installed in the women's bath, filled with soft mist. It allows you to warm your body gradually at a low temperature while hydrating the skin and relaxing. Even those who do not like dry saunas can enjoy it easily, and the quiet space is appealing for a deeply soothing experience that loosens both mind and body.

Cold Bath

Cold Bath

19°C

Water QualityNatural Water (Groundwater, Spring, etc.)

Capacity2people

Men'sWomen's

A luxurious cold plunge bath using well water. Its deepest point of 110 cm is its defining feature, allowing you to cool your entire body while standing or by sinking in deeply. The soft feel of natural water is pleasant, gently tightening a body warmed by the sauna.

Business Hours

Monday
10:00〜22:00
Tuesday
10:00〜22:00
Wednesday
10:00〜22:00
Thursday
10:00〜22:00
Friday
10:00〜22:00
Saturday
10:00〜22:00
Sunday
10:00〜22:00
Holiday
10:00〜22:00

Closed Days: None

Address

〒289-1135 Chiba Prefecture, Yachimata City, Koyaru 616

View on Google Maps

Website

https://koyaru-morinoyu.jp/
Onsen & Spa Facilities (Super Sento, Sauna, Spa)

Gender Access

Gender Separated

🚫
Tattoo Policy
No Tattoos
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