Kosai No Yu

小斉の湯

Mark it and it goes on your passport, with 20 drops. What's the passport?

Can I go?

Day visit ·

Yes

TattoosAllowedUnverified

Private bathYesto book ()

The baths

Special here

MountainsMountains and ridges around you as you soak.

Baths and water

Yes
OnsenUses natural hot spring water
Yes
Outdoor Bath. Open-air outdoor bath
Yes
Indoor Bath. Enclosed indoor bathing area
No
Mixed BathingShared bathing area for all genders

Also here

Washing· ✓ Yes
Towels✓ Yes

Not known yet: Sauna, Cold Bath, Room Onsen, Kids, Dining, Rest Area, Parking, and Day-Use Private Bath. Been there? Tell us.

Hot Spring Sources1

What kind of spring each one is () and what is in it, from its analysis.

Water treatment

Treated and recirculated(partial disclosure)

from Article 18 disclosure

Added water
Yes
Reheated
Not disclosed
Recirculated
Not disclosed
Disinfected
Not disclosed
Bath additives
Not disclosed

蓼科三室源泉

Tateshina Mimuro Spring

Mixed source

塩

Chloride

+ Sulfate

Hot source · 63°C

Known good for

Warmingcold sensitivity
Circulationtired legs
Aches & jointsstiff shoulders

An acidic sodium chloride-sulfate spring — weakly acidic, hypotonic, and notably hot at the wellhead (62.6 C, among Japan's hottest natural sources). The chloride lead gives a salty, heat-retaining body, layered with quiet sulfate depth. The supplier dilutes the water with cold water before it reaches the bath because the source itself is too hot to enter directly.

Analyzed Jun 20, 2004·長野県衛生公害研究所

Explore the water

Documents1

The water analysis certificate () and other papers, as photographed.

Reviews1

Mariia

1 year ago

Higaeri near work. Founded ages ago. The sign said it's the only acidic high-altitude hot onsen in Nagano Prefecture, with acidity comparable to Kusatsu. Kakenagashi, diluted with water since the source temperature is 62 degrees. 700 yen; for an additional 800 yen you can get a kashikiri bath. Two women's and two men's rotenburo, but in winter only two operate. The rotenburo pool is split in half — one side feels like 39, the other 42. The photo shows the view from the women's rotenburo; the men's one apparently has no fence. Note: the indoor and outdoor baths are in different locations (it's quite a walk to the rotenburo). If visiting both, you need to go to the indoor bath first, then get dressed again and walk to the outdoor one. Showers are only in the indoor area; the outdoor one has two hot/cold water taps. Shampoo is provided, but washing up in the cold is quite a challenge.