A massive redevelopment in Tokyo reunites developer and architect

Mitsui Fudosan and SOM join forces to create OH-1, a mixed-use complex with a prominent public square.

September 23, 2016 |

The OH-1 redevelopment project in Tokyo, one of that metro's biggest projects, is designed to recall the past and look forward to the future. Image: courtesy SOM / © Methanoia

One of the largest redevelopments in Tokyo’s history is underway.

The project, known as OH-1 (it is located in Tokyo’s Ohtemachi business district), will consist of two high-rise buildings with 360,000 sm (3.88 million sf) of total floor space, and a landscaped public open space. The redevelopment, which covers 20,900 sm, will be adjacent to the Imperial Palace East Gardens.

OH-1’s mixed-use programming includes office space, a luxury hotel, retail, and cultural facilities. It is scheduled for completion in 2020.

The project, whose construction began on May 18, was initiated by the developer Mitsui Fudosan, and will provide a new corporate headquarters for Mitsui & Co., one of Japan’s largest trading companies. The developer and the project’s design architect, Skidmore, Owings & Merrill (SOM), have worked together before on big projects, including the 2.6-hectare (280,000-sf) Nihonbashi 2 Chrome Redevelopment, which also includes two office towers with combined floor space of 201,456 sm, and is scheduled for completion in 2018.

SOM’s design for OH-1, says the company, sets out to balance tradition and innovation. The 160-meter-tall, 31-story Tower A, which faces the Imperial Palace, is the lower of the two high rises, and harmonizes with surrounding buildings. The use of glass and granite cladding is “inspired” by traditional Japanese woodworking techniques.

Tower B, at 39 stories (five below ground) and 200 meters tall, is clad in glass and steel, a nod to the contemporary Japan and the Tokyo skyline in which this building will be embedded.

Both towers will facilitate natural ventilation and strive toward energy efficiency.

“Our design bridges Tokyo’s past and future—honoring the historical and cultural significance of its site, and … signaling Japan’s status at the forefront of technology and innovation,” said Mustafa Abadan, SOM’s Design Partner, in a prepared statement.


OH-1's two towers differ in their scale, massing, and materiality. Image: courtesy SOM / © Methanoia


The 6,000-sm public space, which will be constructed on the western edge of the site after the buildings are completed, will be landscaped with native trees, and include a reflecting pool and a plaza for outdoor events, as well as a multipurpose hall overlooking the park and plaza.

The park’s design preserves and enhances the setting of the historic cultural monument Masakado’s Shrine, honoring the 10th-century samurai Taira no Masakado, who led a rebellion against Kyoto’s central government. The park also will have direct access to Tokyo’s public transit system.   

According to Mitsui, OH-1’s design is being supervised by a joint venture of Nikken Sekkei Ltd. and Kajima Corporation. The project’s GC is Kajima Corporation. 

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