Sato Family Residence (Mitsubiki): Main House and Okujodan
Cross the Chikuma River northwest of central Ueda and follow the road that hugs the foot of the hills, and you reach Kamishiojiri, a village of old houses lined up against the slope. One of them, large and turned to face south, rewards a second look. The roof changes halfway along. The western wing wears a hip roof of thatch; the eastern wing rises two storeys under clay pantiles, and along its ridge sit two small raised roofs, like miniature roofs perched on the roof itself.
Those little structures are called koshi-yane, monitor roofs fitted with high windows for ventilation, and they signal what this building really was. It was a home, but it was also a workplace for making silkworm eggs. The formal name is long: the Sato Family Residence (Mitsubiki), Main House and Okujodan. It covers about 288 square metres. The western half of the main house is divided into six rooms in three rows, and a separate thatched wing, the okujodan — a raised formal reception room — projects to the northwest. The core of the house dates to the late Edo period, roughly 1751 to 1830, and reached its present shape through later remodelling and an early-Showa expansion.
Kamishiojiri, where the nation's silkworm eggs were made
To understand the house, it helps to know the trade. Japan's silk industry split into distinct crafts: raising silkworms, reeling thread from cocoons, and, as a craft of its own, producing the eggs from which good silkworms hatch. This last was sanshu, the silkworm-egg business, and Kamishiojiri became its foremost centre in the country. Producers here bred sturdy moths, had them lay eggs onto paper cards, and sold those cards to silk farmers across Japan.
The Sato head family is said to have started making silkworm eggs here in the Kanbun era, between 1661 and 1673. Other producing households followed, and by the closing years of the Edo period the district had become a name known well beyond Japan. The timing mattered. In Europe a silkworm disease, pebrine, had spread through the 1850s and 1860s and wrecked sericulture there. Demand for healthy eggs crossed the sea, and of the silkworm eggs Japan exported, the Ueda area accounted for around a third, much of it produced right here in Kamishiojiri.
"Mitsubiki" is the house name of one branch of the Sato family, set apart from the main line in 1727. The branch served as shoya, the village headman, during the Edo period, and like the main house it carried on the egg trade until the middle of the twentieth century. The residence of its master, Sato Onoshichi, was prominent enough to be drawn in Nihon Hakuranzu, a collection of copperplate engravings published in 1897.
A house that grew with its industry
The Sato Family Residence (Mitsubiki) was listed as a Registered Tangible Cultural Property on 24 June 2021. The registration system, lighter than the "designation" given to National Treasures and Important Cultural Properties, is meant for buildings that are protected while still in use. The criterion cited here is that the property contributes to Japan's historic landscape.
What makes the place worth a visit is that it is not a single building. Registered on the same day, alongside the main house and okujodan, were eight more structures: a silkworm-rearing building, a storehouse, a disinfection room, a document storehouse, a grain storehouse, a miso storehouse, a household shrine, and a gate: nine listings in all. They were not built at once. They accumulated as the egg business prospered. The old main house and okujodan were enlarged, the various storehouses and the shrine were renovated, the gate was moved here from elsewhere, and a two-storey rearing building went up new. Later, to disinfect the tools of the trade, a room sealed inside with lime plaster was added, bringing the count of rearing rooms to nine.
Read together, the cluster records how one household absorbed a craft and reshaped itself around the work it demanded. That visible process — an estate taking form in step with an industry — is what the listing recognises.
What to look for
Start with the roof. The two monitor roofs riding the tiled eastern ridge are the giveaway of a silkworm-egg house. Rooms where moths were bred and eggs handled needed air and light; the high windows of the monitor roofs let heat and damp escape, helping keep temperature and humidity in check. The seam where the thatched western hip roof meets the tiled two-storey wing tells the same story of additions made over time.
One practical note about the thatch: it is currently covered with sheet metal as a temporary measure to protect it from the weather, so its natural texture is hard to read, though the broad pitch of the hip roof still reads clearly. White lime-plastered storehouses stand beside the main house, lending the scene the composed look characteristic of the Shiojiri streetscape.
Keep one thing in mind. This is a private home where people still live, and the interior is not open to the public; what you can see is the exterior from the road. Please be considerate of the residents when you stop to look. Even glimpsed over the wall and through the gate, the bearing of a former silkworm-egg house comes through plainly.
Nearby, in Japan's "silk capital"
A short walk away stands the Former Sato Family Residence (Fujimoto), the main line of the family. The head house, which for a time took "Fujimoto" as its name, had its own group of buildings registered in 2024. Its main house was lost to a fire in 1927, leaving the centre of the estate open, but the rearing buildings and storehouses still convey the old scale.
Within a few minutes' walk is the Fujimoto Sanshu History Museum. Housed in the offices of the silkworm-egg company Fujimoto Sanshu (later Fujimoto Kogyo) and opened in 2009, it holds more than ten thousand items: old documents and tools of egg production passed down in the Fujimoto family. Admission is free, but you must contact the museum in advance to visit. The nearest station is Nishi-Ueda on the Shinano Railway, about a nine-minute walk away; the station opened in 1920 as "Kita-Shiojiri" at the petition of the local silkworm-egg producers.
Closer to the town centre are reminders of the reeling side of the trade, including the Former Tokidakan Silk Mill (an Important Cultural Property) and the offices of the Ueda Sericulture Cooperative. Egg-making, cocoon-raising, thread-reeling: half a day here lets you trace the whole arc of the silk story through one town.
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Q&A
- Can I go inside the house?
- No. The Sato Family Residence (Mitsubiki) is a private home that is still lived in, and the interior is not open to the public. You can view the exterior from the road. If you want to see a silkworm-egg estate and its tools up close, the nearby Fujimoto Sanshu History Museum is the place to go (advance booking required).
- What exactly was the "silkworm-egg business"?
- It was the trade of producing silkworm eggs and selling them to silk-farming households. Producers raised hardy moths, had them lay eggs onto paper cards, and shipped those cards out. It was a separate step from raising silkworms or reeling thread, and Kamishiojiri became nationally known for this egg-making.
- What are the little roofs on top of the roof for?
- They are monitor roofs (koshi-yane), built for ventilation. Rooms used for silkworms needed careful control of temperature and humidity, and the high windows let heat and moisture escape. They are a common feature of silkworm-egg houses.
- How does the "Fujimoto" main house differ from the "Mitsubiki" branch?
- Both are Sato households and both made silkworm eggs. "Fujimoto" is the house name of the main line; "Mitsubiki" is the branch that split off in 1727. The estates of both families are Registered Tangible Cultural Properties.
- How do I get there?
- The nearest station is Nishi-Ueda on the Shinano Railway. Kamishiojiri lies along the old Hokkoku Kaido highway, and the streets within walking distance of the station still hold houses that recall the silkworm-egg trade. It is a residential area, so explore quietly and on foot.
Basic Information
| Name | Sato Family Residence (Mitsubiki), Main House and Okujodan |
|---|---|
| Location | 90 Minamigawa, Kamishiojiri, Ueda City, Nagano Prefecture |
| Category | Registered Tangible Cultural Property (Building) |
| Date registered | 24 June 2021 |
| Registration criterion | Contributes to the historic landscape of Japan |
| Period | Late Edo period (c. 1751–1830); remodelled in the late Edo period, enlarged and remodelled in the early Showa era |
| Structure | Wooden, two storeys; thatched roof (temporarily covered with sheet metal); building area approx. 288 m² |
| Count | 1 building |
| Registration no. | 20-0571 |
| Notes | Registered the same day as eight further structures on the estate: a silkworm-rearing building, storehouse, disinfection room, document storehouse, grain storehouse, miso storehouse, household shrine, and gate (nine listings in total). Still in use as a private residence; interior not open to the public. |
References
- Database of National Cultural Properties (Agency for Cultural Affairs): Sato Family Residence (Mitsubiki), Main House and Okujodan
- https://kunishitei.bunka.go.jp/bsys/maindetails/101/00013788
- Cultural Heritage Online (Agency for Cultural Affairs): Sato Family Residence (Mitsubiki), Main House and Okujodan
- https://bunka.nii.ac.jp/heritages/detail/591490
- Cultural Properties of Ueda City (Ueda Citizens' ICT Promotion Center): Sato Family Residence (Mitsubiki)
- https://museum.umic.jp/bunkazai/document2/127.php
- Shinshu Ueda Tourism Association: Tracing the path of "Silk Capital Ueda"
- https://ueda-kanko.or.jp/blog/santoueda1/
- Shinshu Ueda Tourism Association: Fujimoto Sanshu History Museum
- https://ueda-kanko.or.jp/spot/fujimotorekishikan/
Last verified: 2026.06.20