Otemachi-One is the largest mixed-use development in Tokyo’s Otemachi district. Comprising two towers, the project brings offices, retail, event halls, a Four Seasons Hotel, and new public space to the edge of the Imperial Palace in a bustling urban center. At this prominent location, Otemachi-One accentuates Tokyo’s history while signaling the city’s position at the forefront of technology and innovation.

The shorter tower—a 160-meter-tall building and the headquarters for Mitsui & Co., one of Japan's largest trading companies—faces the palace, and responds to the historic building through its scale and through a materiality that is attuned to the neighboring structures. Its detailing, inspired by traditional Japanese joinery and woodworking techniques, reinterprets this craftsmanship in masonry and glass to harmonize with the walls surrounding the palace. Conversely, the taller tower, which rises 200 meters, embodies the aesthetics of contemporary Japan with a facade of glass and steel. Its 40 stories house additional office space as well as the Four Seasons Hotel at the top.

Both towers are designed with cavity walls and ventilated mullions that bring in fresh air. The buildings include a range of additional sustainable features that reduce energy use, from efficient lighting to automatic blinds. The project also presented the opportunity to improve disaster preparedness in the Otemachi district—the buildings feature the most effective seismic damping structures available, and are built to the highest standard of safety and security in Japan.

Public amenities include a basement-level commercial area which offers a variety of retail and restaurants, a direct connection to the Tokyo Metro, and health and wellness services for tenants. The event space, Otemachi Mitsui Hall, is located on the third floor of the Mitsui & Co. building. At ground level, just across from the Imperial Palace East Gardens, a new 6,000-square-meter plaza will be one of the largest green spaces in the area when completed in 2022. This public space, called Otemachi One Gardens, will feature a reflecting pool and native plants and accommodates outdoor programming. The design also preserves the site of Masakado's Shrine, seamlessly integrating the historical monument within the new park.