A sky-high observation bath overlooking the Ina Valley and the Southern Alps, plus a superb beautiful-skin hot spring
Nagano Iida City
"Sangitei Honkan, Castle in the Sky" is a hot spring inn perched on the hill where Iida Castle once stood in Iida City, Nagano Prefecture. Its "Iidajo Onsen," gushing from 1,300 m underground, boasts a high alkalinity close to pH 9.8 and is highly praised as a beautiful-skin hot spring with a silky, lotion-like feel. From the observation indoor bath and open-air bath, you can take in sweeping panoramic views of the Ina Valley and the Southern Alps. It also features a mist sauna filled with fine steam containing hot spring minerals, and a full range of facilities for private family baths and day-use bathing.
TypeNatural Hot Spring
A panoramic large bath using the in-house spring, Iidajo Onsen, which gushed from 1,300 m underground. This alkaline hot spring has a silky texture and helps remove old sebum and dead skin cells, leaving the skin smooth. You can enjoy a luxurious soak in the panoramic indoor bath and open-air bath with large windows overlooking the Southern Alps and the city of Iida.
TypeNatural Hot Spring
A fully reservation-based private family bath where you can enjoy the hot spring in privacy. You can have the same beautiful-skin natural hot spring, touted as a "lotion-like bath," as the large bath all to yourself with family or friends, without worrying about other people watching.
Sauna TypeMist Sauna
Capacity3people
A mist sauna equipped in the large bath area and filled with fine, steam-like mist containing hot spring minerals. With a mild temperature setting that is gentle on the body, it slowly and comfortably encourages perspiration. It is kind to the skin, provides moisture, and offers excellent moisturizing and relaxation effects. Available from 12:30 to 22:00.
Closed Days: None
641-10 Ote-machi 2-chome, Iida City, Nagano Prefecture 395-0034
Gender Access
Gender Separated
The above applies to the communal (shared) baths. At facilities with private baths or private saunas, guests with tattoos may still be able to bathe. Please check with the facility for details.
Curated by an expert who visits onsen and sauna facilities every day and has explored 300+ locations — only facilities confirmed to be truly exceptional are featured.
Learn moreA sky-high observation bath overlooking the Ina Valley and the Southern Alps, plus a superb beautiful-skin hot spring
Nagano Iida City
"Sangitei Honkan, Castle in the Sky" is a hot spring inn perched on the hill where Iida Castle once stood in Iida City, Nagano Prefecture. Its "Iidajo Onsen," gushing from 1,300 m underground, boasts a high alkalinity close to pH 9.8 and is highly praised as a beautiful-skin hot spring with a silky, lotion-like feel. From the observation indoor bath and open-air bath, you can take in sweeping panoramic views of the Ina Valley and the Southern Alps. It also features a mist sauna filled with fine steam containing hot spring minerals, and a full range of facilities for private family baths and day-use bathing.
TypeNatural Hot Spring
A panoramic large bath using the in-house spring, Iidajo Onsen, which gushed from 1,300 m underground. This alkaline hot spring has a silky texture and helps remove old sebum and dead skin cells, leaving the skin smooth. You can enjoy a luxurious soak in the panoramic indoor bath and open-air bath with large windows overlooking the Southern Alps and the city of Iida.
TypeNatural Hot Spring
A fully reservation-based private family bath where you can enjoy the hot spring in privacy. You can have the same beautiful-skin natural hot spring, touted as a "lotion-like bath," as the large bath all to yourself with family or friends, without worrying about other people watching.
Sauna TypeMist Sauna
Capacity3people
A mist sauna equipped in the large bath area and filled with fine, steam-like mist containing hot spring minerals. With a mild temperature setting that is gentle on the body, it slowly and comfortably encourages perspiration. It is kind to the skin, provides moisture, and offers excellent moisturizing and relaxation effects. Available from 12:30 to 22:00.
Closed Days: None
641-10 Ote-machi 2-chome, Iida City, Nagano Prefecture 395-0034
Gender Access
Gender Separated
The above applies to the communal (shared) baths. At facilities with private baths or private saunas, guests with tattoos may still be able to bathe. Please check with the facility for details.
Curated by an expert who visits onsen and sauna facilities every day and has explored 300+ locations — only facilities confirmed to be truly exceptional are featured.
Learn more