Former Main House of the Yamaguchi Mankichi Residence

A Concrete House Built Against the Next Earthquake

The Former Main House of the Yamaguchi Mankichi Residence (旧山口萬吉邸主屋, Kyū Yamaguchi Mankichi-tei Shuoku, also written Kyu Yamaguchi Mankichi-tei) is a reinforced concrete mansion in Kudankita, Chiyoda City, Tokyo, completed in 1927 and entered on Japan's register of Tangible Cultural Properties on 10 May 2018. It occupies the high ground above Kudanzaka, the slope that gave the district its name, roughly five minutes on foot from Yasukuni Shrine and the Nippon Budokan.

The Agency for Cultural Affairs records a single structure of reinforced concrete, three storeys above ground with one basement level, and a building area of 280 square metres. The same entry names Kigo Shichirō as the architect responsible for the design and Naitō Tachū for the structure, and describes a heavy wall-bearing frame handled lightly in the Spanish manner then in fashion.

Construction began in January 1926 and the house was finished in October the following year, according to the history published by the building's current operator.

The client was Yamaguchi Mankichi, fifth in his family to carry that name. Born in 1897 into a Niigata family whose fortune came from trade in Nagaoka, he crossed to the United States before turning twenty and stayed about eight years. Back in Tokyo he met Naitō Tachū, then teaching at Waseda University.

Three years before the first concrete was poured, the Great Kantō Earthquake of 1923 had flattened much of the city around them. That sequence explains a great deal about the house that followed.

Why the Register Calls It a Model of Design

Registered Tangible Cultural Properties are entered under one of three grounds. This house was registered under the first of them, "a model of design" (造形の規範となっているもの), with the registration number 13-402. Two qualities carry the case, and they belong to two different men.

Naitō Tachū (1886-1970) chose a wall-bearing reinforced concrete system, in which the walls themselves carry the load rather than a frame of columns and beams. The walls run 24 centimetres thick, eight sun in the old measure. The operator states that the resulting seismic performance sits well above the standard required by current Japanese code, and that converting the building in 2018 called for no additional reinforcement at all.

Naitō went on to design the structure of Tokyo Tower and the second Tsūtenkaku in Osaka, and is widely called the father of earthquake-resistant design in Japan. The Agency for Cultural Affairs entry adds a detail worth holding onto: Naitō's own house, built in 1926, used the same wall-bearing method and was likewise a collaboration with Kigo.

Kigo Shichirō (1884-1955) supplied the language of the surfaces. Fourth son of the Kigo family, court architects for generations, he trained at Obayashi before going independent. His other work includes Bansui-sō in Matsuyama, built in 1922 and now an Important Cultural Property, and the main building of the Ehime Prefectural Office of 1929. Here he reached for the Spanish idiom that Japanese architects were borrowing from California in the 1920s: round arches, stucco render, curved barrel tiles.

One point of record needs flagging. The national database credits Kigo and Naitō only. The operator's own account of the house adds a third architect, Imai Kanetsugu (1895-1987), the man who first introduced Gaudí to a Japanese audience, and notes that Yoshida Tetsurō stood in on site during a long spell when Kigo was abroad. Readers will meet both versions in print. The Agency for Cultural Affairs listing is the narrower one.

Wall-bearing construction extracts a price. Walls that thick cannot be taken out, so the plan is cut into many small rooms, and generous spaces exist only on the third floor and in the basement. Rather than fight this, the design turned it into a hierarchy: rooms for receiving guests, rooms for the family, servants' quarters, storage and machine rooms, each with its own character across four levels.

What Survived, and How You Can See It

Look for the half-outdoor rooms. A screen porch opens off the ground floor towards the garden, a veranda runs along the second floor, and the third floor gives onto a roof terrace. The garden is pulled into the building vertically rather than merely framed by a window, and the seasons come with it.

The large third-floor room was laid out as a dance hall. In the basement, a central space of arched piers now serves exhibitions and talks, and a former strongroom has been fitted out as a tea room, floor and walls and nothing else.

Furniture and joinery were commissioned from Kajita Megumi (1890-1948), who worked on the house of the politician Hatoyama Ichirō and on the Meiji Seimei Building. The operator says the bill for the furnishings came to roughly what the building itself had cost. Most of those pieces are gone: they were sent to Nagaoka in 1945 to escape the bombing and burned in the rail freight car while in transit. A number of fittings, light fixtures and the original coal boiler equipment remain in place.

The house itself came through the firebombing of 10 March 1945 because it was concrete. Occupation authorities requisitioned it afterwards and housed an officer here; foreign government bodies and the Fulbright Commission leased it for close to two decades after that. Yamaguchi's son and his family moved back in 1963.

In 2018 the Tokyu Corporation, Takenaka Corporation and Toho Leo took a joint master lease from the owner. Takenaka handled the renovation design across a total floor area of 839 square metres, and the building reopened as kudan house, run by NI-WA. The conversion took the 2020 newcomer prize in the Architectural Institute of Japan's Selected Architectural Designs and the 33rd BELCA Award of 2024 in the Long Life category.

Plan your visit around one fact: kudan house is a corporate members-only business salon, hired as a whole building, and there are no walk-in tours. The realistic route inside is an exhibition. Art and design events open to the public with advance booking have run here repeatedly, among them the CURATION⇄FAIR Tokyo exhibitions. Photography indoors is arranged with the operator rather than assumed. The gate and wall along the street, registered separately on the same day, can be looked at from the pavement whenever you pass. Tokyo Metro Kudanshita Station exit 1 is about 400 metres away, a walk of five minutes, and the operator asks visitors not to come by car because parking nearby is scarce.