Dokuzawa mineral spring Kaminoyu
毒沢鉱泉 神乃湯どくさわこうせん じんのゆ
Day Use
YesDay-use opening days are irregular, so check the official calendar on the inn's website or call ahead (0266-27-5526).
Bathing costs 1,000 yen for adults and 500 yen for children (age 3 through elementary school), tax included.
Bathing & Water
Uses natural hot spring water
A cold mineral spring (含鉄(II)-アルミニウム-硫酸塩冷鉱泉, 10°C source, pH2.5) rather than a naturally hot spring; the site and the inn's 日本秘湯を守る会 membership both use 温泉/秘湯 terminology throughout.
Enclosed indoor bathing area
Cold water plunge bath, typically used after sauna
The unheated source (10°C) is bathed directly; guests alternate between the cold source tub and a heated tub.
Capabilities
Private onsen bath in guest rooms, for overnight guests only
All three room categories (新館/本館/旧館) explicitly state バスなし (no bath in room).
Policies & Services
Welcomes children and families
Children are welcome (day-use price set for ages 3 to elementary school) but must be able to bathe/stay quietly; guests unable to do so, adult or child, are asked to refrain from visiting.
Shower, wash stations, soap and shampoo provided
Rinse-in shampoo and body soap are provided; one reviewer suggests bringing your own conditioner since only rinse-in shampoo (no separate conditioner) is supplied.
Towels available to rent or borrow
Listed on the private-room (個室) usage page alongside a separate towel FOR SALE (販売タオル 200円) — the rental item is distinct from the sale item.
Relaxation space for after bathing
Google's editorial summary also mentions lounge areas (ラウンジエリア).
On-site or nearby parking available
One reviewer notes the lot faces the uphill approach road and can be a little tricky to park in.
Views
ForestHighlights
Drinking SpringPrograms
About
Dokuzawa Kosen Kaminoyu is a single-inn ryokan in the hills above Shimosuwa, with fourteen tatami rooms split across three wings. The bath is built around a rare, iron-rich cold spring with a faintly sour taste, drawn straight from the source into one tub and warmed in a second, so you move back and forth between properly cold and hot. It's drunk as well as bathed in, traditionally taken for digestion. The inn dates to 1934, when the first owner's sick child reportedly recovered after bathing here, giving the place its name, Kaminoyu (神乃湯), "Water of the Gods." A shrine to a dragon deity sits over the spring, and a statue of Benzaiten (弁財天) watches over the hall inside. It's a member of the Association for the Preservation of Secluded Hot Springs (日本秘湯を守る会): plain and old-fashioned rather than polished, built for quiet soaking and simple country cooking rather than amenities.
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Last updated July 22, 2026