A 1928 Shopfront on the Old Koshu Kaido
The Mimura Precious Metals Store building (三村貴金属店店舗, Mimura Kikinzokuten Tenpo) stands on the old Koshu Kaido highway in the Suwa district of Suwa City, Nagano Prefecture, was completed in 1928, and was entered on Japan's national register of Tangible Cultural Properties on 28 October 2011.
It is a two-storey timber building with a sheet-iron roof and a floor area of about 78 square metres. Two things make it worth stopping for. The first is the front wall, which has almost nothing to do with the wooden house behind it. The second is who put that front wall there.
Buildings of this type are called kanban kenchiku, literally signboard architecture. The name was coined by the architectural historian Fujimori Terunobu and a fellow researcher, who presented it at the Architectural Institute of Japan convention on 11 October 1975. It describes a shop-and-dwelling that keeps an ordinary Japanese timber frame but covers its street face with copper sheet, mortar, tile or slate, worked up into a flat Western-looking screen. The form spread rapidly in Tokyo after the 1923 Great Kanto Earthquake, since a non-combustible facing was both a fire measure and a cheap way to look modern. Fujimori was born in 1946 in Nagano Prefecture, in Chino, a short train ride from this shop.
Why This One Went on the Register First
The Agency for Cultural Affairs records the contractor as Suwa Kenchiku K.K. and the designer as Oguchi Heisuke, a director of that firm. Its entry also notes that many kanban kenchiku survive in Suwa, and that this building was the first of them to be registered. The criterion applied was contribution to the historic character of the national landscape.
The family that owns it tells the design story differently. According to the shop's own account, the facade was worked out jointly by the head of the family, a metalsmith, and his younger brother, a chased-metal artist who held an appointment to the Imperial Household. The two accounts do not sit easily together, and a visitor should treat the Agency record as the documented one and the family version as tradition.
What is not in dispute is what the facade looks like. A semicircular arch sits at the centre of the upper storey, framing the shop name, with ribs radiating inside the arch like the spokes of a fan. A shallow cornice runs above. The family points out the resemblance to the arched entrances of Tokyo Station, completed in 1914, and given that both brothers worked in Tokyo the comparison is at least plausible. Stand across the street and the reading holds up: this is a piece of metalwork enlarged to the size of a house, made by people whose trade was making small things in metal.
The Mimura had reason to want a striking front. Their line reaches back to 1626, when the family arrived in Suwa as retainers accompanying Matsudaira Tadateru, a son of Tokugawa Ieyasu, into exile. They later lived as townspeople. In the Meiji period they adopted a young man descended from the Tatekawa school of shrine carpenters, a Suwa lineage known for architectural sculpture; he turned instead to tankin, the hammering of sheet metal, and won selection at the national art exhibitions that later became the Nitten. Records show he presented a tobacco case to the Crown Prince, the future Emperor Showa, in 1919. The family opened a metal workshop in 1907 on this site, which had been samurai residential land at the point where the castle town met the road up to Takashima Castle, and where the family had earlier run a restaurant called Masakiya.
Fire settled the rest. The old townhouse burned in April 1926, and the present building went up in 1928, three years after the Kanto earthquake had made the signboard front fashionable. The register also lists repairs in 1969 and 1995.
Walking Up from Kamisuwa Station
The building sits three to five minutes on foot from JR Kamisuwa Station, on the shopping street that follows the old Koshu Kaido, now National Route 20. Its immediate neighbour, a bridal and artificial-flower shop also run by a branch of the same family, carries its own registration, so two registered shopfronts stand side by side. Walk the block slowly and other survivors of the same decade appear along the street; Suwa kept far more of this architecture than most towns its size.
For a long time the shop was simply a shop, and at one point demolition was under consideration. Instead the family reopened the building in 2024 as a small complex. The ground floor now holds a cafe bistro called minerai, named after the French word for ore, and the upper floor is let out as a rental kitchen fitted for confectionery work and as an event space usable as a gallery, pop-up shop or studio.
That change matters for anyone planning a visit, because it means the interior can actually be entered. The published hours are 11:30 to 22:00, with Wednesdays closed and occasional irregular closures, so confirming on the shop's website or social media before travelling is sensible. The exterior can be photographed from the pavement at any time; inside, ordinary cafe manners apply, and asking before photographing other customers is the courteous approach. There is no admission charge, since the building is a business rather than a museum.
One caution on the address. The cultural property register gives the lot number as Suwa 1-10101-1, while the current street address in use is Suwa 1-5-20. They refer to the same building.
If time allows, Lake Suwa is about ten minutes' walk in the other direction from the station, and the Takashima Castle grounds lie roughly fifteen minutes to the southwest, at the end of the road this shop once stood beside.
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Q&A
- Can visitors go inside the Mimura Precious Metals Store building, and are there opening hours?
- Yes. Since a 2024 renovation the ground floor houses a cafe bistro called minerai and the upper floor is rented out as a kitchen and event space. Published hours are 11:30 to 22:00, closed Wednesdays plus occasional irregular days, so checking the official website before travelling is advisable. There is no admission fee; the building operates as a business.
- What is kanban kenchiku, and why is the Mimura Precious Metals Store building an example of it?
- Kanban kenchiku, or signboard architecture, is a shop-and-dwelling type that keeps a conventional Japanese timber frame but faces the street with a flat Western-looking screen of copper, mortar, tile or slate. The term was introduced by the architectural historian Fujimori Terunobu in 1975. The Mimura building has exactly that arrangement: a decorated street facade with a semicircular arch and radiating ribs, fixed to an ordinary two-storey wooden structure behind.
- Who designed the Mimura Precious Metals Store building?
- The Agency for Cultural Affairs names Oguchi Heisuke, a director of the contractor Suwa Kenchiku K.K., as the designer. The owning family's own account instead credits the facade to two brothers of the household who worked in metal. The Agency record is the documented one; the family version should be read as tradition passed down rather than established fact.
- How do I reach the Mimura Precious Metals Store building from Kamisuwa Station?
- It is a three to five minute walk. Leave JR Kamisuwa Station on the town side and follow the shopping street that runs along the old Koshu Kaido, now National Route 20. The building is on that street, next door to another registered shopfront belonging to a branch of the same family.
- When was the Mimura Precious Metals Store building registered, and what does registration mean?
- It was registered on 28 October 2011 under number 20-0387, using the criterion of contribution to the historic character of the national landscape. Registration is a lighter form of protection than designation as an Important Cultural Property or a National Treasure: the owner notifies the state before substantial alteration rather than applying for permission, which is part of why continued commercial use is possible.
Basic Information
| Name | Mimura Kikinzokuten Tenpo (三村貴金属店店舗), the Mimura Precious Metals Store building |
|---|---|
| Location | Suwa 1-10101-1, Suwa City, Nagano Prefecture (current street address in use: Suwa 1-5-20) |
| Designation | Registered Tangible Cultural Property (building); registration number 20-0387 |
| Year Designated | Registered 28 October 2011 |
| Quantity | 1 structure |
| Dimensions | Two-storey timber construction, sheet-iron roof, floor area about 78 square metres; built 1928, repaired 1969 and 1995 |
| Owner | Privately owned; no owner recorded in the Agency for Cultural Affairs database |
| Public Access | Exterior visible from the street at any time. Interior open as a cafe bistro and rental space, 11:30 to 22:00, closed Wednesdays and on irregular days; no admission fee |
References
- National Database of Designated Cultural Properties, Agency for Cultural Affairs: Mimura Kikinzokuten Tenpo
- https://kunishitei.bunka.go.jp/heritage/detail/101/00008990
- Cultural Heritage Online: Mimura Kikinzokuten Tenpo
- https://online.bunka.go.jp/heritages/detail/246090
- Mimura Kikinzokuten official site
- https://mimura-royalmetal.com/
- Mimura Kikinzokuten official site: the family story
- https://mimura-royalmetal.com/story.html
Last verified: 2026.08.21