The long storehouse behind the courtyard
Tenkoku Art Museum Rear Storehouse (Former Hirano Family Rear Storehouse, 篆刻美術館裏蔵棟) is a stone warehouse of 2 storeys in Chuocho, Koga City, Ibaraki Prefecture, built in 1920 (Taisho 9) and listed as a Registered Tangible Cultural Property in 1998 (Heisei 10).
Where its neighbour on the street front goes up, this one goes sideways. Koga City gives the frontage as 14.544 meters and the depth as 4.545 meters, a building area of 66.10 square meters. That is a strip barely wider than a corridor and more than 3 times as long, laid out along the south side of the courtyard and turned to face it.
It has a tiled gable roof, Kirizuma-zukuri in Japanese terms, with no ornament on it. The Agency for Cultural Affairs calls the building a standard gabled stone storehouse, and the word standard is doing real work in that sentence. Tenkoku Art Museum Rear Storehouse was the working end of the Hirano property: goods went in, goods came out, and nobody was meant to admire it from the road.
That is also why it survives so legibly. A storehouse nobody decorated is a storehouse nobody kept modernising. The stonework, the proportions and the roof frame are all still readable as what a Taisho-period merchant family in Koga actually built for storage.
Why both storehouses were registered
Tenkoku Art Museum Rear Storehouse was entered on the national register as a Registered Tangible Cultural Property on 9 October 1998, with registration number 08-0005, under the criterion for buildings contributing to the historic landscape of the country. Its counterpart on the street was registered the same day as number 08-0004. The two are separate entries, not one listing split in half.
Registering both is the point. A single surviving warehouse tells you a merchant family owned a warehouse. A front building and a rear building still standing at right angles across their original courtyard tell you how the property was organised: display and reception towards the street, bulk storage behind. In the old castle town of Koga, that pairing has rarely survived whole, and the rear building is the half that tends to go first.
Because registration permits continued use, the building could be converted rather than mothballed. An office wing and an earth-floored eaves space were attached at either end during the work, and the interior became Exhibition Rooms 3, 4 and 5 of the Tenkoku Art Museum, which opened in the spring of 1991 (Heisei 3) as the first museum in Japan given over to tenkoku, the art of seal engraving.
The roof truss, the monitor and the courtyard
The upper floor is the reason to climb the stairs. The ground floor of Tenkoku Art Museum Rear Storehouse is divided into 2 rooms, but the floor above is left as 1 undivided space, and the roof structure over it is exposed. It is a king post truss: a triangle of rafters with a single vertical member dropped from the ridge to the centre of the tie beam. That is a Western carpentry type, and finding it inside a Japanese stone storehouse of 1920 is a small piece of evidence about how quickly imported framing methods reached provincial builders. Compare it with a Wagoya, where posts of varying length stand on a horizontal beam instead.
Then look for daylight. A monitor roof, a raised section running along the ridge with openings in its sides, sits on top of the building. Storehouses are dark by design, since the whole purpose of thick stone walls is to admit as little as possible. The monitor lets light down the middle without cutting a single extra window into the wall, and on a bright day you can watch where it lands on the floor.
The exhibitions in Rooms 3, 4 and 5 change by theme, which means the interior of Tenkoku Art Museum Rear Storehouse looks different from one visit to the next. In 2026, for the museum's 35th anniversary, the stone storehouses themselves were written into the exhibition alongside the seal engraver Ishii Soseki, so the building was on show as well as the work hanging in it.
Outside, stand in the courtyard. The Front Storehouse rises on the north side, close enough that the two roofs frame a rectangle of sky between them. It is the one spot where the plan of the old Hirano property reads at a glance.
Visiting Tenkoku Art Museum Rear Storehouse
Opening hours are 9 a.m. to 5 p.m., last admission 4:30 p.m. Adults pay 200 yen, elementary through high school students 50 yen, and groups of 20 or more 150 yen each. A 600 yen combination ticket adds the Koga Historical Museum and the Koga Museum of Literature. Rates can differ during special exhibitions.
The museum closes on Mondays, staying open when a national holiday falls on one and closing the next weekday instead, and also on the 4th Friday of every month and over the New Year. Koga City publishes a calendar of opening days for the year.
No photography rule is published on the city's pages, so ask at the desk before using a camera inside Tenkoku Art Museum Rear Storehouse. There is no restriction on photographing the buildings from the public street outside.
Koga Station on the JR Utsunomiya Line is about 8 minutes away on foot, roughly 60 minutes from Ueno or Shinjuku. From the west exit, walk straight ahead, turn left at the crossing beyond the florist, cross the Hon-cho 2-chome intersection and continue to the signal named for the museum. Shin-Koga Station on the Tobu Nikko Line is about 25 minutes on foot. The city's Gururin-go community bus serves the museums on its western route from Koga Station west exit. There is a gravel car park directly opposite the entrance.
Because the rear building sits behind the front one, you reach it by walking through the courtyard, which is worth doing slowly rather than as a transit. Seal engraving workshops run by advance booking in a study room a minute or 2 towards the station. 40 minutes covers both storehouses at an unhurried pace.
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Q&A
- Can visitors go inside Tenkoku Art Museum Rear Storehouse?
- Yes. It houses Exhibition Rooms 3, 4 and 5 of the Tenkoku Art Museum and is open whenever the museum is, from 9 a.m. to 5 p.m. with last admission at 4:30 p.m. Adult admission is 200 yen.
- What is the roof structure inside Tenkoku Art Museum Rear Storehouse?
- A king post truss, left exposed over the upper floor. A single vertical member runs from the ridge down to the middle of the tie beam. It is a Western framing type, used here in a Japanese stone storehouse built in 1920.
- When was Tenkoku Art Museum Rear Storehouse built and registered?
- Built in 1920 (Taisho 9) as a storehouse of the Hirano family, and registered as a Registered Tangible Cultural Property on 9 October 1998 under number 08-0005.
- How do I get to Tenkoku Art Museum Rear Storehouse from Koga Station?
- Walk about 8 minutes from the west exit of Koga Station on the JR Utsunomiya Line, going straight out, turning left past the florist and crossing the Hon-cho 2-chome intersection. The rear building is reached through the courtyard behind the street-facing one.
- How large is Tenkoku Art Museum Rear Storehouse?
- Koga City records a frontage of 14.544 meters, a depth of 4.545 meters and a building area of 66.10 square meters, on 2 floors. The ground floor is divided into 2 rooms and the upper floor is a single space.
Basic Information
| Name | Tenkoku Art Museum Rear Storehouse (Former Hirano Family Rear Storehouse) |
|---|---|
| Location | 5655-1 Chuocho 2-chome, Koga City, Ibaraki Prefecture, and other locations |
| Designation | Registered Tangible Cultural Property (structure) |
| Year Designated | Registered in 1998 (Heisei 10) |
| Quantity | 1 building |
| Dimensions | Frontage 14.544 meters, depth 4.545 meters, building area 66.10 square meters |
| Owner | Koga City |
| Public Access | Open as Exhibition Rooms 3, 4 and 5 of the Tenkoku Art Museum, 9 a.m. to 5 p.m., admission charged |
References
- Agency for Cultural Affairs, National Database of Designated Cultural Properties: Tenkoku Art Museum Rear Storehouse
- https://kunishitei.bunka.go.jp/heritage/detail/101/00000812
- Koga City, Registered Cultural Property: Tenkoku Art Museum Rear Storehouse (Former Hirano Family Rear Storehouse)
- https://www.city.ibaraki-koga.lg.jp/soshiki/bunka/15/siteitourokubunnkazai/kogabunkazaikennzoubutu/2417.html
- Koga City, Tenkoku Art Museum: Visitor Information
- https://www.city.ibaraki-koga.lg.jp/soshiki/tenkoku/16188.html
- Koga City, Tenkoku Art Museum: Access
- https://www.city.ibaraki-koga.lg.jp/soshiki/tenkoku/16190.html
- Koga City, Tenkoku Art Museum 35th Anniversary Special Exhibition
- https://www.city.ibaraki-koga.lg.jp/soshiki/tenkoku/exhibition/22746.html
Last verified: 2026.09.07