Baths may be unavailable during the coldest part of winter.
Adults (junior-high age and up) are 500 yen, children (elementary age and under) are 300 yen. Day-use bathing may be turned away if the baths are busy with overnight guests.
Uses natural hot spring water
Open-air outdoor bath
Enclosed indoor bathing area
Private bath available for day-use visitors or hotel guests to reserve
A separate free-standing building with its own private outdoor bath; use is roughly 1 hour.
Shared bathing area for all genders
Baths are gender-separated (men's/women's), each with its own indoor + attached outdoor bath; no mixed bathing offered.
Welcomes children and families
Discounted day-use and lodging rates published for elementary-age and younger children.
Shower, wash stations, soap and shampoo provided
Towels available to rent or borrow
Bath towel (バスタオル) is available for an extra fee — a rurubu.jp/andmore listing puts it at ¥100 rental; hand towel is included free.
On-site or nearby parking available
Sanei-so is a small onsen inn in Norikura Kogen. Its milky white water, with a faint scent of sulfur, is piped down from the Yugawa-gensen spring (湯川源泉) partway up Mt. Norikura, kept flowing fresh (kakenagashi, 掛け流し) around the clock. Men's and women's baths are separate, each pairing an indoor tub with its own attached outdoor bath, and a stand-alone building nearby holds a private outdoor bath you can book for about an hour. Day-use bathing is open to visitors who aren't staying the night.
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Last updated July 26, 2026