OKUMURA CORPORATION + MR STUDIO Co.,Ltd.: Winner of World Design Awards 2025. Kyoei Steel is Japan’s leading steel producer, specializing in recycling iron scrap. Using electric arc furnaces, the company transforms scrap iron—construction waste like H-beams, cars, mobile phones, vending machines, and medical needles—into high-quality steel products for construction. This transformation of “once-used iron” into valuable steel forms the foundation of its business. Building on this expertise, Kyoei Steel has advanced into environmental recycling, utilizing technologies to render industrial waste harmless.

This project, at Kyoei Steel’s Yamaguchi Division, replaces and consolidates aging office and welfare buildings, enhancing site efficiency. By centralizing dispersed office functions, the new building improves productivity and provides a better working environment, while enriching welfare facilities, including dining halls and bathhouses. The exterior design, inspired by steel billets stored at the plant, symbolizes regenerating scrap iron into structural steel. The facade features five stacked billets with varied attributes, enhanced by two vertically divided stairwell volumes, forming a composition of seven billets. Each billet’s unique colors and textures reflect Kyoei Steel’s product diversity and identity in a striking aesthetic. Inside, steel products from the Yamaguchi Division, such as equal-angle steel, flat bars, and deformed bars, are prominently featured as finish materials, celebrating their raw strength and aesthetic potential. Materials like angle steel (L30x30, 50×50, 75×75), flat bars (FB-32, 50), I-bars (I-BAR-44, 75), and deformed bars (10φ, 25φ, 38φ) were used for walls, ceilings, and the company’s barcode pattern. This barcode, serving as a symbol of traceability, embodies the company’s commitment to transparency and accountability in its recycling process, visually connecting material flows with corporate identity. The stairwell features 93 wires (6φ) stretched across 20 meters, with five types of angles and seamless lighting. A QR code of the company’s website is integrated into the horizontal plane, while staircase handrails use randomly arranged angles and deformed steel bars. On the west side, similar steel bars cover the stairwell from floor to penthouse, interacting with handrails and lighting to emphasize verticality. This interplay of light, shadow, and raw steel highlights Kyoei Steel’s technological strength and innovative spirit. Dynamic lighting effects embody the company’s brand identity. By showcasing materials and integrating values, the project harmonizes functionality and design. Rooted in the company’s recycling philosophy, it presents a prototype for architecture merging sustainability, innovation, and identity with a unique spatial experience.

Project Details:-
Firm
OKUMURA CORPORATION + MR STUDIO Co.,Ltd.

Architect
Masahiko Tokunaga + Nobuaki Miyashita

Project Name
Kyoei Steel Yamaguchi Division New Office Building

Project Category
Corporate & Office Building (Built)

Team
Masahiko Tokunaga, Tetsuya Nagayoshi / OKUMURA CORPORATION, Nobuaki Miyashita, Yukari Hirose, Miki Kase / MR STUDIO Co., Ltd.

Project Location
Yamaguchi, Japan

Country
Japan

Photography ©Credit
©Kenta Sato / JXPhoto Co., Ltd. ,Nobuaki Miyashita / MR STUDIO Co.,Ltd.

OKUMURA CORPORATION, founded in 1907, is a Japanese general contractor specializing in civil engineering and building construction. Guided by “reliable management” and “sincere construction,” it delivers high-quality infrastructure and advances sustainability through technologies such as seismic isolation, OCMS shield tunneling, renewable energy, and aquaculture initiatives, reflecting its innovative evolution.
MR STUDIO Co., Ltd., established in Tokyo in 2017, creates concept-driven architecture that reveals each project’s unique identity and emotional resonance. Integrating signage, lighting, landscape, and product design, the firm crafts contextually precise, innovative, and expressive spaces across residential, office, and cultural typologies.