The Working Heart of an Egg Producer's Estate
The Former Sato Family Residence (Fujimoto) Silkworm Room No. 1 is a two-story, earth-walled rearing house built in 1890 on the estate of a silkworm-egg producer in Kamishiojiri, Ueda, Nagano Prefecture, and it was registered as a Registered Tangible Cultural Property on August 15, 2024. In Japanese it is 旧佐藤家住宅（藤本）一号蚕室, Kyū Satō-ke Jūtaku (Fujimoto) Ichigō Sanshitsu.
A sanshitsu, or silkworm room, is where the worms are raised. The Sato family's head house, trading as Fujimoto, did not sell silk or cocoons. It sold eggs. The healthier the parent moths, the better the product, so the rearing rooms were the most important buildings on the property.
Silkworm Room No. 1 stands near the middle of the lot, its ridge running north to south. It is a gabled, tile-roofed Dozo-zukuri building with a footprint of 63 square meters, repaired in the mid-Showa period and again in 2000. A smaller annex is attached to its north end.
Why It Was Registered
The building was registered for its contribution to the historic landscape of the country. The Agency for Cultural Affairs points to the equipment that survives inside: an underground leaf store, karo fire furnaces, a slatted ceiling, and ventilation openings that can be opened and shut. Together, it says, they convey how the egg trade actually worked.
Each feature had a job. The cellar, called a chosōko, held mulberry leaves, the silkworms' only food, and kept them from drying out. The furnaces warmed the rearing racks on cold spring nights; local reports describe stone fireboxes burning logs and rice husks. The slatted ceiling and adjustable vents let warm, damp air escape so that temperature and humidity stayed within a narrow range.
In other words, feeding, rearing, heating, and airing were all built into a single structure. Silkworm Room No. 1 is a record of Meiji-era egg production written in plaster and timber.
What to Look For
The walls are finished in white Shikkui plaster carried all the way up to seal the eaves, with no exposed wood. That is fire protection, and it makes sense for a building that kept a live furnace inside.
On the south side, the roof of a lean-to Geya doubles as a work deck ringed by a handrail. Set at second-floor height and open to the sun, it was most likely used for airing and drying equipment, a small sign of how closely the work followed the light.
The Agency for Cultural Affairs database has an exterior photograph taken from the southwest and an interior view of the north room upstairs, where the slatted ceiling and vents can be seen.
Visiting Silkworm Room No. 1
The Former Sato Family Residence (Fujimoto) Silkworm Room No. 1 stands on private land owned by Fujimoto Kogyo Co., Ltd., and neither the interior nor the grounds are open to the public. Requests to visit must go to the owner. We found no published guidance on photography.
Because the building sits in the middle of the estate, little of it can be seen from outside. For a closer look at the tools of the trade, the nearby Fujimoto Sericulture History Museum holds equipment and records from the family's egg business; visits are arranged in advance through Fujimoto Kogyo.
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Q&A
- Can you visit the Former Sato Family Residence (Fujimoto) Silkworm Room No. 1?
- No. It stands on private property and is not open to the public. Anyone hoping to see it should contact the owner, Fujimoto Kogyo Co., Ltd.
- When was the Former Sato Family Residence (Fujimoto) Silkworm Room No. 1 built?
- It was built in 1890, repaired in the mid-Showa period and in 2000, and registered as a Registered Tangible Cultural Property on August 15, 2024.
- What is the karo furnace in the Former Sato Family Residence (Fujimoto) Silkworm Room No. 1?
- It is a fire furnace used to warm the rearing room so the silkworm racks would not chill in early spring. Logs and rice husks were reportedly burned in it.
- What is under the Former Sato Family Residence (Fujimoto) Silkworm Room No. 1?
- An underground store for mulberry leaves, the silkworms' food, designed to keep the leaves from drying out.
- How big is the Former Sato Family Residence (Fujimoto) Silkworm Room No. 1?
- It is a two-story earth-walled building with a footprint of 63 square meters, gabled and tile-roofed, with an annex attached on the north.
Basic Information
| Name | Former Sato Family Residence (Fujimoto) Silkworm Room No. 1 |
|---|---|
| Location | 91 Minamigawa, Kamishiojiri, Ueda, Nagano Prefecture |
| Designation | Registered Tangible Cultural Property (Building) |
| Year Designated | Registered 2024/8/15 (Reiwa 6) |
| Quantity | 1 building |
| Dimensions | Dozo-zukuri, 2 stories, tiled roof, building area 63 square meters |
| Owner | Fujimoto Kogyo Co., Ltd. |
| Public Access | Not open to the public (private property) |
References
- Database of National Cultural Properties (Agency for Cultural Affairs): Former Sato Family Residence (Fujimoto) Silkworm Room No. 1
- https://kunishitei.bunka.go.jp/bsys/maindetails/101/00015011
- Toshin Journal: Former Sato Family Residence registered as a national cultural property (Japanese)
- https://tjournal.co.jp/local/ueda/post-17134/
- Weekly Ueda: Former Sato Family Residence (Fujimoto) and the silk history of Ueda (Japanese)
- https://www.weekly-ueda.com/post/%E8%9A%95%E9%83%BD%E4%B8%8A%E7%94%B0%E3%81%AE%E6%AD%B4%E5%8F%B2%E3%82%92%E7%89%A9%E8%AA%9E%E3%82%8B-%E6%97%A7%E4%BD%90%E8%97%A4%E5%AE%B6%E4%BD%8F%E5%AE%85%EF%BC%88%E8%97%A4%E6%9C%AC%EF%BC%89
- Ueda City Tourism Association: Fujimoto Sericulture History Museum (Japanese)
- https://ueda-kanko.or.jp/spot/fujimotorekishikan/
Last verified: 2026.09.25
