A Silkworm Room with a Ventilation Roof Running the Length of Its Ridge
At the south end of the Sato family compound in Kamishiojiri, on the edge of Ueda City, stands a two-storey wooden building running east to west, its gabled, pantiled roof carrying a koshi-yane, a raised monitor roof, along the entire length of the ridge. The upper floor holds three board-floored rooms, and each one has windows on both its north and south faces, so that air can be drawn straight through. This is a sanshitsu, a room built for raising silkworms.
The building has a floor area of about 118 square metres. Two doorways open on the north side of the ground floor, where the interior is divided into two earthen-floored rooms. The outer walls are plastered up under the eaves and finished in a middle coat of render, while the two gable ends are finished in white lime plaster. Every part of the design serves the silkworm: the monitor roof and the paired windows let a rearer manage the temperature and humidity that the insects demand.
Silkworms are delicate. They suffer in damp and in dryness alike, and a room that could be aired and steadied through the seasons was the difference between a good crop of eggs and a failed one. The whole structure reads as a working instrument for that task.
The Silkworm-Egg Families of Kamishiojiri
The Sato family, known by the house-name Mitsuhiki, were sanshu-ka, producers of silkworm eggs, in Kamishiojiri. This is the work of breeding and selling the eggs from which good silk-spinning worms hatch, a trade distinct from the rearing of cocoons or the reeling of raw silk. Kamishiojiri specialised in it, and the silkworm room is one of several structures of the Mitsuhiki residence entered on the national register.
Kamishiojiri sits along the old Hokkoku Kaido highway, and from the Edo period its households turned to silkworm-egg production until, by the closing years of the shogunate, the district had become one of the largest such centres in Japan. The reputation reached far beyond the country: as European silkworm stocks were ravaged by disease in the nineteenth century, demand for robust Japanese eggs rose sharply. Ueda's long association with the trade earned it the name santo, the silk capital.
The silkworm room was registered as a Tangible Cultural Property in 2021, under the criterion that it contributes to the historic character of the national landscape. Registered Tangible Cultural Property is a lighter designation than Important Cultural Property, created in 1996 to protect the broad stock of buildings from the modern centuries. The Mitsuhiki house should not be confused with the nearby former Sato Residence known as Fujimoto, a related but separate property registered later, in 2024.
What to Look For
The silkworm room is part of a private residence, the home of the family firm's president, and is not generally open to visitors. From the public road, though, the monitor roof along the ridge is the feature to pick out. Once you know to look for that long raised cap, you begin to see it on house after house through Kamishiojiri, because so many of the village's families built the same kind of ventilated room for the same trade. The narrow lanes branching off the highway, and the sturdy walls raised against the valley wind, belong to the same sericultural townscape.
One small local detail worth watching for is the cat tile, a roof ornament in the shape of a cat, set up to ward off the rats that preyed on silkworms. The streets of Kamishiojiri are, in effect, an open-air record of a craft that once supplied the world.
Around Kamishiojiri
The district lies about five minutes on foot from Nishi-Ueda Station on the Shinano Railway, west of central Ueda in the Chikuma River valley. To understand what the silkworm rooms were for, the best stop is the Fujimoto Sericulture History Museum a short way off, which holds documents, tools, and images of the silkworm-egg business and can be visited by prior arrangement.
Ueda keeps other monuments to the silk age. The former Tokitakan silk mill, a national Important Cultural Property, preserves a tall wooden cocoon warehouse and early reinforced-concrete stores from the era when machine reeling transformed the city. Ueda-tsumugi, counted among Japan's three great pongee silks, still carries the thread of the trade into the present. Checking access and opening details before setting out is sensible.
- 📍 Plan Your Visit to Nagano
- Find tours, activities & transport passes near Sato Family Residence (Mitsubiki) Silkworm Room
- [ Matsumoto Castle & Kamikochi Hiking Tours ]
Q&A
- What is a silkworm room?
- A sanshitsu is a building designed for raising silkworms, fitted with features such as a monitor roof and paired windows that let the rearer control temperature and humidity.
- Can I go inside?
- No. The silkworm room is part of a private residence and is not generally open. The exterior and the wider Kamishiojiri townscape can be appreciated from the public street.
- What did Kamishiojiri produce?
- It specialised in silkworm eggs, the breeding stock of the silk industry. By the late Edo period it was one of Japan's largest silkworm-egg producing districts.
- Is this the same as the Fujimoto residence?
- No. The Mitsuhiki silkworm room is a distinct property. The nearby former Sato Residence known as Fujimoto is a related but separate house, registered in 2024.
Basic Information
| Name | Sato Family Residence (Mitsuhiki), Silkworm Room |
|---|---|
| Structure | Timber two storeys, tiled gabled roof with full-length monitor roof, floor area about 118 square metres |
| Date | Mid-Meiji period (1883-1897) |
| Designation | Registered Tangible Cultural Property (registered 24 June 2021) |
| Compound | Residence of a silkworm-egg producing family; several structures registered |
| Location | Minamigawa 90 and others, Kamishiojiri, Ueda City, Nagano |
| Viewing | Private residence, not generally open; exterior visible from the street |
References
- National Database of Designated Cultural Properties (Agency for Cultural Affairs)
- https://kunishitei.bunka.go.jp/bsys/maindetails/101/00013789
- Cultural Heritage Online (National Institutes for Cultural Heritage)
- https://bunka.nii.ac.jp/heritages/detail/591490
- Shinshu Ueda Tourism Association, Tracing the Silk Capital of Ueda
- https://ueda-kanko.or.jp/blog/santoueda1/
Last verified: 2026.06.22