Shinjuku Sumitomo Building

The Shinjuku Sumitomo Building is a 52-story skyscraper in Nishi-Shinjuku defined by its distinctive triangular form with cut-off corners. A large central atrium dominates the interior, while a glass-covered public plaza called Sankaku Hiroba distinguishes the exterior.

The structure was completed in 1974 and stood as the tallest building in Japan and Asia at its opening. This marked a turning point in regional architecture and reflected Japan's economic strength during that era.

The building is called the 'Triangle' by local residents because of its triangular shape and cut-off corners, a nickname that shows how people in Tokyo connect with geometric architectural design. This informal name is part of everyday conversation and ties the structure to the community around it.

The building is easy to visit thanks to several nearby subway stations and good accessibility throughout the complex. The public plaza is open around the clock and offers views of the architectural design and the surrounding district.

The structure uses INAX Terracotta bricks that reference Karami bricks from the Besshi Copper Mines, connecting it to Japan's industrial heritage. This material choice creates a subtle link between contemporary architecture and traditional Japanese mining history.

Location: Nishi-Shinjuku

Inception: April 4, 1974

Architects: Nikken Sekkei

Floors above the ground: 52

Elevators: 38

GPS coordinates: 35.69127,139.69260

Latest update: December 17, 2025 09:07