What the Hoshi Onsen Chojukan Annex Is
The Hoshi Onsen Chojukan Annex (法師温泉長寿館別館, Hōshi Onsen Chōjukan Bekkan) is a two-story timber guest wing built in 1940 on the west bank of the Hoshi River in Nagai, Minakami Town, Gunma Prefecture, registered as a Registered Tangible Cultural Property on August 3, 2006.
While the Main Building and the Hoshi-no-Yu bathhouse stand on the east bank, the Hoshi Onsen Chojukan Annex sits across the river, running north to south. It is 37 meters long but only 9 meters deep, the slenderest of the three registered buildings, with a footprint of 276 square meters. The gabled roof, in the Kirizuma-zukuri form, is sheet metal rather than the cedar bark used on the two Meiji-era buildings.
Why the Annex Was Registered
The Hoshi Onsen Chojukan Annex was registered under the criterion of contributing to the historic landscape of the country, as registration number 10-0190.
Younger than its Meiji neighbors, it was still 66 years old when registered. The Agency for Cultural Affairs points to its Shikkui lime-plastered walls and to the single row of rooms opening toward the river, and describes the overall design as restrained. The long pale wall running along the valley is a large part of how the inn looks from either bank.
What to Look For at the Annex
A Facade Turned to the River
On both floors of the Hoshi Onsen Chojukan Annex, the rooms line up in a single row. On the river side each room has a wide veranda-corridor, or hiroen, closed by glass doors that reach the floor. On the far side is a single-loaded corridor with waist-high windows. Glass faces the water; wall and small windows face the hillside.
The river side faces east, so the whole elevation is best seen from the Main Building side across the water. Two tiers of glass doors give it a character quite unlike the Main Building, where the eye goes first to the cedar-bark roof.
Ten Identical Rooms
According to the inn, the Annex has 10 guest rooms, all with the same plan: an 8-mat main room and a 4-mat entry space. Every room looks onto the Hoshi River and has its own toilet. From some rooms the Main Building and Hoshi-no-Yu are visible across the water.
The inn describes the window glass as Taisho-era glass, with a slight waviness that softens the view outside. The building itself was completed in 1940, and no document confirming when the glass was made has been found.
Visiting the Hoshi Onsen Chojukan Annex
The Hoshi Onsen Chojukan Annex is a guest wing, and its interior is reserved for overnight guests. There are no building tours.
For the exterior, stand on the east bank near the Main Building and Hoshi-no-Yu and look across the river. The glazed river elevation can only be seen square-on from the opposite bank.
The inn's website sets out no photography policy. Because each window belongs to someone's room, take care that no guests appear in pictures taken from outside. Travel and bathing information is on the Hoshi Onsen Chojukan page.
- 📍 Plan Your Visit to Gunma
- Find tours, activities & transport passes near Hoshi Onsen Chojukan Annex
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Q&A
- When was the Hoshi Onsen Chojukan Annex built?
- In 1940. It was registered as a Registered Tangible Cultural Property on August 3, 2006.
- How does the Hoshi Onsen Chojukan Annex differ from the Main Building?
- The Annex stands on the west bank of the Hoshi River with a sheet-metal roof and plastered walls. The Main Building is on the east bank under a cedar-bark roof.
- Do rooms in the Hoshi Onsen Chojukan Annex have river views?
- Yes. The inn says all 10 rooms face the Hoshi River, with a veranda-corridor and glass doors on the river side.
- Do rooms in the Hoshi Onsen Chojukan Annex have private toilets?
- Yes, every room has one, according to the inn. All rooms share the same plan of an 8-mat room with a 4-mat entry.
- Can I see the Hoshi Onsen Chojukan Annex on a day visit?
- The interior is for overnight guests only. The exterior can be seen across the river from the Main Building side.
Basic Information
| Name | Hoshi Onsen Chojukan Annex |
|---|---|
| Location | 650 Nagai, Minakami-machi, Tone-gun, Gunma Prefecture, and others |
| Designation | Registered Tangible Cultural Property (Building) |
| Year Designated | Registered August 3, 2006 |
| Quantity | 1 building |
| Dimensions | 37 meters by 9 meters; footprint 276 square meters |
| Owner | Hoshi Onsen Chojukan Co., Ltd. |
| Public Access | Operating guest wing. Exterior visible; interior for overnight guests only |
References
- Agency for Cultural Affairs, Database of National Cultural Properties: Hoshi Onsen Chojukan Annex
- https://kunishitei.bunka.go.jp/bsys/maindetails/101/00005584
- Cultural Heritage Online: Hoshi Onsen Chojukan Annex
- https://online.bunka.go.jp/heritages/detail/170892
- Hoshi Onsen Chojukan official website: Rooms
- https://hoshi-onsen.com/rooms/
Last verified: 2026.09.25
