Sato Family Residence (Mitsubiki)

A Branch Family's Silkworm-Egg Estate

The Sato Family Residence (Mitsubiki) is the estate of a silkworm-egg producing family in Kamishiojiri, Ueda, Nagano Prefecture, where nine structures, from a late Edo main house to a late Meiji disinfection room, were each registered as a Registered Tangible Cultural Property on June 24, 2021. In Japanese it is 佐藤家住宅（三ツ引）, Satō-ke Jūtaku (Mitsubiki); Mitsubiki is the household's trade name.

Japan's silk economy ran on three separate trades: raising silkworms for their cocoons, reeling thread from the cocoons, and a third that visitors rarely hear about, producing the eggs themselves. Egg producers bred healthy moths, collected their eggs on paper cards and sold the cards to farmers. Kamishiojiri made its name in this last trade. According to Ueda City, the head of the Sato clan, a household that for a time called itself Fujimoto, began making silkworm eggs here in the Kanbun era (1661 to 1673), and over the following generations the business took root across the village.

Between the end of the Edo period and the first years of Meiji, a silkworm disease known as pebrine swept through Europe and all but wiped out sericulture there. Buyers turned to Japan. Eggs from the Ueda area are said to have made up around a third of Japanese exports, much of it produced in Kamishiojiri, which is how the village came to be called the finest egg-producing district in the country.

The Mitsubiki household branched off from the head family in 1727 and served as village headman (Shōya) under the Edo shogunate. It kept making silkworm eggs until the middle of the twentieth century.

Nine Structures Around the Main House

The main house stands on the north side of the lot, facing south. Its western half is single-story under a thatched hip roof (Yosemune-zukuri, Kayabuki), currently sheathed in sheet metal for protection; its eastern half rises two stories under a gabled tile roof, with two raised ventilation roofs, koshi-yane, riding the ridge. The okujodan, a thatched wing holding the formal reception rooms, projects to the northwest.

Storehouses gather to the west. The Document Storehouse, ridge running north to south, and the Miso Storehouse, ridge running east to west, both stand just west of the main house. Farther west, on a stone retaining wall at the northwest corner of the lot, a tiny Inari shrine serves as the household shrine and faces south.

South of the main house are the compact, east-facing Grain Storehouse and the Disinfection Room, whose ground floor was sealed with plaster. To the southeast, the Storage Shed, with rearing rooms upstairs, runs north to south along the east edge of the lot, and the gate opens on the same side. At the far south end lies the long, two-story Silkworm Room, its raised ventilation roof running the full length of the ridge.

Living quarters and storage sit to the north and west; the buildings used for silkworms sit to the south and east. The Agency for Cultural Affairs describes the individual buildings as shaping the east edge, the center, the west side and the northwest corner of the estate, so that the nine listings frame the entire property.

An Estate That Grew With the Egg Trade

The buildings are not all of one date. The main house and okujodan go back to the late Edo period (about 1751 to 1830), were altered at the end of Edo and enlarged again in the early Showa era. The household shrine and the Storage Shed date from late Edo (about 1830 to 1868), and the gate, also late Edo, was moved here in the middle Meiji years. The Silkworm Room is mid-Meiji (about 1883 to 1897), the Grain Storehouse was built in 1897 and the Document Storehouse in 1898, while the Miso Storehouse and the Disinfection Room belong to late Meiji (about 1898 to 1912).

Ueda City ties this sequence to the fortunes of the business. As egg production boomed from late Edo through Meiji, the old main house and okujodan were extended, the storehouses and the shrine were renovated, the gate was relocated and the two-story Silkworm Room went up new. The estate appears, labeled as the residence of the egg producer Sato Onoshichi, in volume 12 of Nihon Hakuranzu, a book of copperplate views published in 1897. After that came the Disinfection Room, its interior plastered so that rearing tools could be disinfected, and the estate's rooms for raising silkworms reached nine in all.

One detail does not line up. The national database dates the Document Storehouse to 1898 and the Miso Storehouse to late Meiji, yet Ueda City counts both among the buildings shown in the 1897 engraving. The print may record them before a later rebuilding, but the sources do not settle the point, so both accounts are given here.

The nine registration numbers run consecutively from 20-0571 to 20-0579, and every listing rests on the same criterion: contribution to the historic landscape of the country. Ueda City stresses that the buildings keep their period appearance and together show how the estate took shape as the egg business grew. What was registered, in other words, is less a single house than a working compound assembled building by building.

The head family's estate, the Former Sato Family Residence (Fujimoto), stands close by and had six of its buildings registered in 2024. With both the main line and the branch listed, Kamishiojiri offers two neighboring examples of how silkworm-egg families laid out their homes.

Visiting and Access

The Sato Family Residence (Mitsubiki) is private property, and none of the nine buildings is open to the public. We found no published open days or visiting arrangements. What you can see is limited to views from outside the lot, chiefly along the east side where the gate and the Storage Shed stand. This is a residential neighborhood, so keep your voice down and give the residents their privacy.

The nearest station is Nishi-Ueda on the Shinano Railway, one stop and about five minutes from Ueda Station. The estate lies in the Kamishiojiri district east of the station, roughly 600 meters away in a straight line, or around ten minutes on foot. The Shinshu Ueda Tourism Association publishes a half-day walking route from Nishi-Ueda Station that links Ueda's silk-industry sites with the old streets of Kamishiojiri.

Documents and tools from Kamishiojiri's egg trade, drawn from the head family's archive, are kept at the Fujimoto Sericulture History Museum (248 Kamishiojiri), a private museum that asks visitors to get in touch before coming.