About the Iwao Family Residence Main House
The Iwao Family Residence (Former Nihongan Pharmaceutical Works) Main House (岩尾家住宅（旧日本丸製薬所）主屋, Iwao-ke Jūtaku Shuoku) is a 3-storey wooden townhouse of the late Taisho era in Mameda-machi, Hita City, Oita Prefecture, and it became a Registered Tangible Cultural Property on January 31, 2003. It went up in the late Taisho era as a 2-storey Machiya with its timber sealed under plaster, and a third-floor lookout was set on top in the early Showa era. That lookout is why locals have long called the building the castle keep of Mameda.
The main house of the Iwao Family Residence fronts the street in Mameda Kami-machi, with a footprint of 171 square meters and a tiled roof. The storehouse adjoins it on the north, and the annex is linked to its rear by a connecting corridor. Today it is the core of the Nihongan-kan museum.
Why It Was Registered
The Iwao Family Residence Main House was registered for contributing to the historic landscape of the country. The Agency for Cultural Affairs describes it as a pharmacy at the very center of Mameda Kami-machi, where the traditional townscape survives. It singles out the small karahafu roof, with its undulating curved gable, over the right end of the ground-floor front, and the great hall on the second floor, finished with a generous use of choice timbers. The agency also notes that residents know the building fondly as the castle keep of Mameda.
After the great fires of the Meiji era, Mameda filled with Igura-zukuri townhouses whose wooden frames were sealed in earthen plaster against fire, and Hita City counts a handful of early Showa three-storey houses among the district's defining features. The Iwao Family Residence Main House carries both traits in a single building: a fire-sealed, white-walled townhouse below, and the extra height an early Showa merchant chose to add above it.
The Great Hall, the Roof Garden and the Lookout
The great hall singled out by the Agency for Cultural Affairs is on the second floor of the Iwao Family Residence Main House. The Nihongan-kan gives its size as 24 tatami mats, and its windows look onto a roof garden laid out at second-floor level. The museum points out that a garden on an upper floor was a great rarity at the time, and a clear sign of how comfortably a prosperous merchant family lived.
The hall also hosts seasonal displays. During the Tenryo Hita Hina Festival in spring, generations of the family's hina dolls are set out here. In autumn the room recreates the golden wedding anniversary celebrated in 1938 by Iwao Shotaro, the fifteenth head of the family, and his wife Wari. Take a moment, too, for the joinery and timbers that the Agency for Cultural Affairs describes as a lavish use of fine woods.
At the top of the stairs, on the third floor, is the lookout, with a view over the Mameda townscape to the mountains ringing the Hita basin. Because of this early Showa addition, the Nihongan-kan describes the building as having four levels and three floors.
Seeing and Visiting the Iwao Family Residence Main House
The exterior of the Iwao Family Residence Main House can be seen from the street at any time. Stand in front and look for the little karahafu roof at the right end of the ground floor, then let your eye climb past the white second storey to the lookout. Knowing that the lookout was added in the early Showa era makes the difference between it and the two storeys below easier to read.
The interior, including the great hall and the lookout, can be visited during the Nihongan-kan's open seasons: February 15 to May 31 in spring and September 1 to November 30 in autumn. Opening hours are 10:00 a.m. to 4:00 p.m., and adult admission is 400 yen. These details were checked on the official Nihongan-kan website on October 6, 2026.
The official website does not say whether photography is allowed inside, so please ask at the reception desk.
- 📍 Plan Your Visit to Oita
- Find tours, activities & transport passes near Iwao Family Residence (Former Nihongan Pharmaceutical Works) Main House
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Q&A
- When was the Iwao Family Residence Main House built?
- It was built in the late Taisho era as a 2-storey townhouse, and the third-floor lookout was added in the early Showa era.
- Why is the Iwao Family Residence Main House called the castle keep of Mameda?
- The nickname compares the tall silhouette of a white-walled townhouse topped by a third-floor lookout to the keep of a castle. The Agency for Cultural Affairs records it as the name residents fondly use.
- Why is the Iwao Family Residence Main House a Registered Tangible Cultural Property?
- It was judged to contribute to the historic landscape of the country, as a building that shapes the townscape at the center of Mameda Kami-machi. It was registered on January 31, 2003.
- Can visitors go up to the lookout of the Iwao Family Residence Main House?
- Yes, during the Nihongan-kan's open seasons, February 15 to May 31 and September 1 to November 30. Adult admission is 400 yen.
- What can be seen in the great hall of the Iwao Family Residence Main House?
- A 24-mat hall finished in fine timbers, with a roof garden outside its windows. Hina dolls are displayed in spring, and in autumn a recreation of the family's 1938 golden wedding celebration.
Basic Information
| Name | Iwao Family Residence (Former Nihongan Pharmaceutical Works) Main House |
|---|---|
| Location | 4-15 Mameda-machi, Hita City, Oita Prefecture |
| Designation | Registered Tangible Cultural Property (Structure) |
| Year Designated | Registered January 31, 2003 |
| Quantity | 1 building |
| Dimensions | 3-storey wooden building, tiled roof, building area 171 square meters |
| Owner | Not listed in the Agency for Cultural Affairs database (opened to the public by Iwao Yakuho as the Nihongan-kan) |
| Public Access | Open in spring and autumn as the Nihongan-kan (10:00 a.m. to 4:00 p.m.; adults 400 yen) |
References
- Database of National Cultural Properties: Iwao Family Residence (Former Nihongan Pharmaceutical Works) Main House (Agency for Cultural Affairs)
- https://kunishitei.bunka.go.jp/heritage/detail/101/00003180
- Agency for Cultural Affairs: Hita City Mameda-machi Preservation District (prepared by Hita City, Japanese)
- https://www.bunka.go.jp/seisaku/bunkazai/shokai/hozonchiku/pdf/94428201_119.pdf
- Nihongan-kan official website
- https://www.nihongan.info/
- Nihongan-kan: Guide to the Building
- https://www.nihongan.info/s-projects-side-by-side
Last verified: 2026.10.06
