Former Kozuma Family Main Building

A Samurai House Above the Harbour Town

The Former Kozuma Family Main House (旧上妻家住宅主屋, Kyū-Kōzuma-ke Jūtaku Shuoku, also written Kouzuma) is a late Edo period samurai residence at 9819 Nishinoomote, Nishinoomote City, Kagoshima Prefecture, on the island of Tanegashima, listed as a Registered Tangible Cultural Property of Japan on 2 May 2017.

Tanegashima lies about forty kilometres off the southern tip of Kyushu, a long low island better known abroad for two things: the arrival of Portuguese matchlock guns in 1543, and the rocket launch site at its southern end. The Kozuma house belongs to neither story directly, and that is part of its interest. It is the domestic architecture of the island's ruling class, still standing on the ground where it was built.

The site occupies a low rise at the southwestern edge of Nishinoomote Fumoto. A fumoto was the Satsuma domain's answer to a castle town. Rather than concentrating retainers in one large city, Satsuma scattered its warrior households into more than a hundred fortified village clusters across its territory, each attached to a local administrative centre. Tanegashima had one, and the Kozuma compound stood inside it. The ground here is open enough that you can read the shape of the land from the front of the house.

The building itself is timber, single storey with a partial upper floor, tile roofed, covering 210 square metres. The plan is unusual and worth taking slowly. Rooms sit in two rows, one behind the other, running north and south. The southern row held the formal rooms used for receiving visitors. The northern row was the family's own space. The eastern room of that northern row is thought to have started out as an earth floored working area before being boarded over at some later point.

What the Roof Space Gave Up

Nishinoomote City bought the property in 2016. In the surveys that followed, the most productive part of the building turned out to be the attic.

Two documents recovered from inside the house have since been designated city cultural properties in their own right, on 10 September 2024. Both are now held at the Teppokan, the city museum near the port.

The first is a licence in the Shintō-ryū school of spear technique, dated to the third month of Tenbun 20 (1551). It was issued by one Minamoto no Nobusada to Taira no Naotoki, a formal name for Tanegashima Tokitaka, the young lord who bought the first Portuguese guns eight years earlier. The document explains how the spear is handled by drawing the human body as muscle and skeleton alone, with the movement traced in red line over the figure. The Tanegashima family chronicle records that Tokitaka studied swordsmanship, spear and staff under Nobusada and received his licence in that month of that year. The sheet found in the Kozuma attic matches the entry.

The second is a paired portrait dated Eishō 10 (1513), showing a man and a woman seated facing one another in clerical robes, with the Lotus Sutra invocation written between them. From the Buddhist name beside the male figure, the pair are taken to be the twenty-second head of the Kozuma family and his wife. It is a gyakushu image, made during the subjects' lifetimes as an act of merit for their own afterlife. Paired husband and wife portraits from medieval Japan are rare, and this one carries both a date and identifiable sitters.

The Kozuma family is said to have come to Tanegashima as deputies for the Kamakura appointed steward of the island, governing it before the Tanegashima lords arrived, and to have served afterwards as the Tanegashima family's senior retainers. Documents of this weight sitting in a wicker basket under the roof are consistent with that account.

Two Dates, One Building

Anyone reading about this house will meet two different construction dates, and it is better to know why.

The Agency for Cultural Affairs register records the main house as late Edo, giving a range of 1830 to 1868, with alterations between 1946 and 1965. That is the official designation data, and it is what the registration was made against.

The city's conservation and use plan, adopted in March 2023, works from a ridge tag found inside the building that points to Kan'en 4 (1751), roughly eighty years earlier. Surveys of the fabric have found marks left by old carpentry tools throughout, and some working methods that appear to reach back further still, to techniques associated with the medieval Muromachi period. Those findings were the grounds for the city designation of 2024.

The two records have not been reconciled in the published sources, and visitors should treat the earlier date as a reading of the evidence rather than a settled fact. What is certain is that later generations kept adding: a second floor, a kitchen, a bathroom, a lavatory, a porch. The restoration now under way has removed those additions, and the stated aim is to return the building to its appearance before the upper floor went on.

Practical note for anyone planning a trip. The house is a working conservation site and does not keep opening hours. Between 2017 and 2019 the city ran five limited openings, and another was held in November 2023, when visitors were taken through the trace survey findings and shown the roof tiles and structural members at close range. These are announced locally and are not on a fixed calendar. Anyone hoping to get inside should contact the Cultural Properties Section of the Nishinoomote City Board of Education, based at the Teppokan, on 0997-23-3215, and confirm access and photography before travelling. The compound and its gate can be seen from the approach at any time.

Getting to the island: high speed boats and car ferries run from Kagoshima to Nishinoomote Port, and Tanegashima Airport is about thirty minutes from the town by car. The Kozuma site lies roughly a kilometre southwest of the port, uphill. The Teppokan itself is about ten minutes on foot from the ferry terminal, and going there first is sensible, since the two documents from the house are on that side of town and the staff who look after the building work from the same address.