Toranomon Hills Station Tower, center, designed by architectural firm OMA, is the latest high-rise addition to central Tokyo's Minato ward. Courtesy of Tomoyuki Kusunose and OMA

TOKYO ― Tokyo presents itself as a sea of densely packed, low-rise buildings punctuated by shrines and islands of sleek steel-and-glass skyscrapers.

Now, the metropolis' cityscape welcomes a new architectural marvel, Toranomon Hills Station Tower, which stands out not just for its height but for its design and multi-purpose functionality.

Designed by architectural firm OMA, this latest skyscraper aligns with the longstanding vision of Mori Building Company, one of Japan's most prominent real estate developers, to transform Tokyo into a "vertical city."

Over the decades, the company has been reshaping Tokyo's skyline with a flurry of multibillion-dollar megacomplexes. Each of these radical (yet also controversial) redevelopments is anchored by several multiple-use skyscrapers that offer offices, retail space and residential units all within a single site, creating a kind of "urban village." Its most famous project is Roppongi Hills, which was completed in 2003, and it now sees the development of the Toranomon Hills complex as well.

Over the years, Mori Building Company, one of Japan's most prominent real estate developers, has been reshaping Tokyo's skyline with a series of multibillion-dollar megacomplexes, including Toranomon Hills. The OMA-designed station tower joins three other buildings previously established in the neighborhood: Mori Tower, Business Tower and Residential Tower. Courtesy of OMA and The Boundary

The 49-story station tower joins three other buildings ―Mori Tower (2014), Business Tower (2020) and Residential Tower (2022) ― previously established in the Toranomon Hills, a neighborhood that spans over 7.5 hectares.

But what sets the new, OMA-designed tower apart from these structures in Toranomon Hills ― and to a certain extent, Mori Building's other high-rises in the city ― is its facade, as well as its noted emphasis on the idea of connectivity.

"The building has a dynamic design where, depending on the view angle within the city, it looks very different," said Shohei Shigematsu, OMA's partner in charge of the project, during an interview with The Korea Times held against the impressive backdrop of Tokyo's panoramic view, Oct. 2.

Toranomon Hills Station Tower's playfully twisted facade is noteworthy considering that it was conceived in the Japanese metropolis known for its stringent building codes necessitated by the high risk of earthquakes. Courtesy of Tomoyuki Kusunose and OMA

The architectural feat is particularly noteworthy considering that it was conceived in a city known for its stringent building codes necessitated by the high risk of earthquakes.

"Here, the building's design has to be constant; it cannot be 'eccentric,' in that its left and right sides should ideally have the same weight and shape," he added.

While meeting the country's rigorous seismic standards, OMA achieved the tower's whimsically torqued facade by dividing the structure into three sections ― a central vertical band sandwiched between two trapezoidal slabs in 180-degree rotational symmetry. The northern slab narrows as it ascends, while the southern counterpart widens, causing the central axis to naturally twist as it goes upward.

Architect Shohei Shigematsu, OMA's partner in charge of the Toranomon Hills Station Tower project / Courtesy of Tomoyuki Kusunose and OMA

The concept of connectivity, both literal and figurative, is another element that remains at the core of the station tower's design for several reasons.

The building stands at the terminus of Shintora-dori Avenue, a major thoroughfare stretching from Tokyo Bay to the city center that is dubbed by some locals as "Tokyo's Champs Elysees." Furthermore, the tower sits directly above the new Toranomon Hills railway station, thus seamlessly integrating with the city's wider transportation network.

Within this context, OMA has inserted spaces with a highly public-oriented character both at the skyscraper's base, which includes a shopping concourse and a station atrium with skylights, and at its top, where you'll find the Tokyo Node housing galleries, a sky garden and an auditorium.

OMA has inserted spaces with a highly public nature at the skyscraper's base, which includes a shopping concourse and a station atrium with skylights. Courtesy of Tomoyuki Kusunose and OMA

"Having a proper public domain (where individuals can gather) is becoming more and more important for a commercial building. It's not like the old days when people thought it should be an either/or," Shigematsu said.

Rather than isolating itself as a "private fortress," the tower aspires to be more "aware of its contextual assets and knitted into the existing city fabric," he continued. "That's why all the rooms and features within it are looking outward and not too much inward."

Meanwhile, the T-Deck, a 20-meter-wide elevated green footbridge, connects the station tower to Shintora-dori Avenue, highlighting street-level walkability ― a virtue that has not been extensively promoted in Tokyo.

The relative underemphasis on walkability is due to the metropolis' remarkable density of aboveground facilities and, somewhat ironically, well-established public transportation network and underground infrastructure.

The T-Deck is a 20-meter-wide elevated green footbridge that connects the station tower to Shintora-dori Avenue. Courtesy of Tomoyuki Kusunose and OMA

"People in Tokyo tend to go from one point to another taking trains. For example, from Shiodome to Toranomon, in people's mental map, it's a couple of stations away. What they often don't realize is that it's actually also just a 15-minute walk," the architect noted.

"This kind of a 'three-dimensional' urban experience ― going underground, coming back up and heading to one's destination ― is easily understood here."

And Mori Building Company's redevelopment projects, which maximize the use of mixed-use skyscrapers, make the most of Tokyo residents' familiarity with such three-dimensional urban living.

By consolidating various building functions ― office, hotel, retail, cultural venue and underground railway station ― within a single high-rise structure, thereby leaving ground-level areas more open and pedestrian-friendly, Toranomon Hills Station Tower embodies the "vertical garden city" philosophy championed by the developer.

"Mori's focus has been on liberating the ground-level expanse for more green or public space," Shigematsu said.

An infinity pool with a panoramic view of the Tokyo skyline is situated atop Toranomon Hills Station Tower. Courtesy of Mori Building Co., Ltd.

Tokyo Node

One of the standout features of Toranomon Hills Station Tower is the Tokyo Node. Spanning the top five floors, the space includes three galleries, a media hall, an auditorium, a sky garden and an infinity pool ― all with a sweeping view of the Tokyo skyline as a backdrop.

It might seem like an inherent fit for the skyscraper, but Shigematsu revealed that the program only came to life after OMA proposed the idea to the real estate company.

In fact, the original building plan only dedicated the tower's floors to office, hotel and retail facilities. "We suggested to our client that we really needed something cultural for the tower. Otherwise, people were going to take it as just another commercial mixed-use structure," he said. The Tokyo Node thus became the last piece of the puzzle.

In a way, the Tokyo Node mirrors the Mori Art Museum ― one of the city's most well-known contemporary art institutions operated by the same client ― and the observation deck sitting atop the Mori Tower in Roppongi Hills.

Spanning the top five floors, the Tokyo Node includes three adjoining galleries that can be integrated to create one expansive venue. Courtesy of Mori Building Co., Ltd.

But the Tokyo Node presents itself as a more versatile and up-to-date cultural space compared to its Roppongi counterpart, according to the architect.

"The Mori Art Museum was built 20 years ago. It's a pure gallery space that hasn't been able to do hypermedia exhibitions. The same goes for the observatory, which is very narrow and inconvenient. But the art (of today) is becoming quite diverse; it's not just paintings or sculptures, but also a lot of media, sound and performance," he observed.

"Here, it's like a hybrid of the two, because all three galleries have suitable dimensions in depth and height (that can cater to diverse forms of contemporary art) and are also facing outward, offering a view of the city's skyline."

The ongoing inaugural performance "Syn: Unfolded Horizon of Bodily Senses" by Rhizomatiks & ELEVENPLAY at the Tokyo Node blends live choreography with mixed-reality (MR) technology. Courtesy of Mori Building Co., Ltd.

The adjoining three galleries can also be integrated to create one expansive venue, as demonstrated in the ongoing inaugural performance "Syn: Unfolded Horizon of Bodily Senses" by Rhizomatiks & ELEVENPLAY, which blends live choreography with mixed-reality (MR) technology.

Shigematsu imagines that the galleries can even be combined with the neighboring auditorium and the rooftop garden to stage the likes of galas, fashion shows and product launches in the future.

An auditorium with a view of Imperial Palace and Tokyo skyline / Courtesy of Mori Building Co., Ltd.

Addressing office oversupply dilemma

Toranomon Hills Station Tower is one of the prominent additions to the office space supply in the Japanese metropolis, where an increasing number of private-led redevelopment projects like Mori's have been replacing low-rise, aging neighborhoods with clusters of skyscrapers.

Such a trend has raised concerns among some local industry insiders about potential oversupply in the office leasing market.

In fact, the office vacancy rate in Tokyo's five central wards ― including Minato, where the station tower is located ― reached a 10-year high of 6.46 percent as of July, according to real estate brokerage firm Miki Shoji, with the spike partly attributed to the pandemic-induced surge in remote work.

"As an architect, the oversupply issue remains a dilemma, of course, since we can't go completely against what our client has asked us to design," Shigematsu said.

This was one of the reasons why OMA proposed capping the tower's top floors with the Tokyo Node, aiming to reduce the volume of office space and accommodate more cultural elements "that can help establish a strong identity for the building."

"Many are now rethinking what the office space should be because people can work almost anywhere. That's why diversity within the building is always a plus for me," he noted, adding that the employees of the tower's corporate tenants have options to work beyond traditional cubicles with access to the pedestrian deck, atriums and outdoor garden.

American artist Leo Villareal's "Firmament (Mori)" (2023), a site-specific light installation, activates the station tower's skybox. Courtesy of Tomoyuki Kusunose and OMA

The station tower represents OMA's "first in several ways," according to the architect.

It's the company's first skyscraper in Japan, as well as its first ground-up building in Tokyo. The tower is also the largest project the office has undertaken in the country.

"Until now, we didn't really have a major skyscraper experience in Asia besides CCTV (China Central Television Headquarters in Beijing) and such. I hope something like this will open up possibilities for us; there is more potential in creating something new and exciting," he said.

"The skyscraper was only born some 150 years ago; it's actually a relatively new (architectural) typology. And I still believe that it could evolve."