Former Kaneko Kentaro Hayama Villa, Onshimatsuso

A Villa That Moved for the Imperial Household

Kyu Kaneko Kentaro Hayama Bettei Onshi Matsuso (旧金子堅太郎葉山別邸恩賜松荘, also written Onshi Matsusō) is a single-storey wooden residence of about 1922 in the Isshiki district of Hayama, Kanagawa Prefecture, entered on Japan's National Register of Tangible Cultural Properties on 4 February 2021. It stands on a slope with the wooded ridge of Mitsugaoka behind it and the water of Isshiki beach in front, a short walk from the Hayama Imperial Villa.

The building covers 199 square metres and divides into two wings. The southern wing carries a gabled roof of pantiles and holds the entrance, the living room and a dining room. The northern wing has a hipped roof over a formal tatami reception room, a second dining room, and Western-style rooms at the rear. Both wings sit low against the hillside, which is part of why almost nobody driving the coast road below notices them.

The house belonged to Kaneko Kentaro (1853–1942), one of the four men who drafted the Constitution of the Empire of Japan. Its present location is not its original one. Kaneko gave up a seafront plot in 1919 because the Imperial Household wanted it, and rebuilt further up the hill. That single fact explains most of what is interesting about the place.

Who Kaneko Kentaro Was

Kaneko was born in 1853 into a samurai family of the Fukuoka domain and studied at the domain academy Shuyukan. In 1871 he travelled to the United States as a privately funded student attached to the Iwakura Mission, accompanying his former lord. He read law at Harvard and returned to a Japan that was inventing its own legal order from scratch.

Working under Ito Hirobumi alongside Inoue Kowashi and Ito Miyoji, he helped draft the constitution promulgated in 1889. Later he held the portfolios of agriculture and commerce, and then of justice, and sat on the Privy Council.

English-language readers may know him best for a different episode. When war with Russia broke out in February 1904, Ito sent him to America because he had known Theodore Roosevelt at Harvard. For roughly eighteen months Kaneko lectured, gave interviews and worked the drawing rooms of the eastern seaboard, arguing Japan's case to a public that had largely expected to side with Russia. When the Portsmouth negotiations stalled over indemnity and Sakhalin, he went to Roosevelt directly at the request of the plenipotentiary Komura Jutaro. He came home in October 1905.

He died in May 1942, aged 89. Hayama had by then been his address for two decades.

The Imperial Villa Rearranges a Neighbourhood

Hayama became a resort because two foreigners recommended it. Erwin Baelz, the German physician who attended the imperial family, and the Italian minister to Japan, De Martino, both praised the climate of this stretch of Sagami Bay in the 1880s. The first summer villa followed within a year or so. The opening of Zushi station on the Yokosuka line in 1889 made the area reachable from Tokyo in an afternoon, and the imperial villa itself was completed in 1894.

Kaneko built his first Hayama house in the late 1880s, near what is now Isshiki Park, with Iwakura Tomosada and Inoue Kowashi as neighbours. In 1919 the Imperial Household Ministry bought all three plots to create an annexe to the imperial villa. The three politicians moved out.

Kaneko relocated to the present hillside around 1922. Local accounts hold that parts of the older house came with him, though the surviving Meiji-period fabric appears to amount to no more than scattered members rather than a whole structure. Hayama town records identify the transplanted portion as the Matsu-no-ma, the pine room, remembered as the room where a dowager empress was received.

After the Great Kanto Earthquake of 1923 damaged much of Tokyo and Yokohama, the family used the Hayama house almost as a permanent residence rather than a summer retreat. Ownership changed after the Pacific War. Repairs and additions were carried out around 1955, and the house was renovated again in 2007. It remains a private home.

Inside the Pine Room

The Matsu-no-ma is the reason the registration file describes this as a house of unusual quality. Its tokonoma alcove uses a henboku, a deliberately gnarled and irregular natural timber, as the display post, next to a biwadana shelf of the kind normally found in tea-influenced reception rooms. The transom between rooms is not the usual pierced woodwork but a copper panel cut with plum blossom and set against bamboo.

Copper transoms are rare. Wood is easier to carve, cheaper, and warmer to the eye, and most villa builders of the period used it without a second thought. Choosing metal here suggests a client who wanted the room to read as slightly formal, slightly imperial, without shouting about it.

The renovation of the 1950s could easily have swept this away. It did not. The evidence of the fabric suggests the owners of the time worked hard to keep the Taisho-period character of the room that had once received a member of the imperial family, and that intention carried through the 2007 work as well.

Elsewhere in the house the timber is described in the registration documents as meiboku, choice figured wood selected for grain rather than for structural convenience. The joinery details differ from room to room instead of repeating a single pattern, which is the mark of a builder given time and money.

Why It Is on the Register

Japan operates two parallel systems for historic buildings, and the distinction matters here. Designation as an Important Cultural Property (jūyō bunkazai) is a strong protective measure applied to a small number of buildings, with heavy restrictions on alteration. Registration as a Tangible Cultural Property (tōroku yūkei bunkazai), introduced in 1996, is lighter: it applies to buildings roughly fifty years old or more, records their value publicly, and asks owners to notify the authorities before major changes while leaving them free to keep living in the house.

Onshi Matsuso is registered, not designated. Its registration number is 14-0289 and it came through in the 97th round of registrations, notified and entered on 4 February 2021. The criterion applied was that the building is a model of its type in design.

The Hayama town assessment adds a second argument. This house carries the history of a seafront villa displaced by the construction of the imperial annexe, and so records how the town developed alongside the imperial presence. It was registered on the same day as Beijuso, the two-storey house Kaneko built nearby in his eighty-eighth year, and the two are best understood as a pair.

What a Visitor Can Actually Do

The house is not open to the public. There are no visiting hours, no admission fee, and no interior access. It is a private residence on private land, screened by planting, and the courteous thing is to leave the residents alone. Photography of the building is not appropriate from within the grounds, and the grounds are not open in any case.

What makes the trip worthwhile is the surrounding ground, all of which is public. Hayama Shiosai Park occupies the site of the former imperial annexe, which is to say the site of Kaneko's first villa. The porte-cochere of the annexe survives as the entrance to the park museum. Isshiki Park nearby covers ground associated with the same cluster of Meiji-era villas.

The Museum of Modern Art, Hayama sits a few minutes away at Isshiki 2208-1, with free outdoor sculpture and a sea-facing restaurant. The Yamaguchi Hoshun Memorial Hall, the house and studio of a Japanese-style painter, stands at Isshiki 2320, almost immediately beside the Kaneko plots. Between these you can walk the whole villa district in an hour.

Access is by bus. From JR Zushi station (east exit, stand 3) or Keikyu Zushi-Hayama station (south exit, stand 2), take the Keikyu bus on route Zu-11 or Zu-12 marked kaigan-mawari, the coastal loop, and get off at Mikagaoka / Kanagawa Kenritsu Kindai Bijutsukan-mae. The ride takes about fifteen to twenty minutes and longer on summer weekends when the coast road backs up. One caution for photographers: the Hayama Imperial Villa itself is off limits to cameras, and guards will stop you from even raising one at the gate.