Construction Begins for the
“Nihonbashi Honcho 1-chome District 5 Project” (Tentative Name),
Japan’s First Nearly ZEB Timber Rental Office Building
Over approximately 31,783 ft3 (900 m3) of Timber to Be Used in Realizing Offices with an All-Wood Structure
November 5, 2025
Mitsui Fudosan Co., Ltd.
Fukuoka Jisho Co., Ltd.
Key Points of this Press Release
- Over approximately 31,783 ft3 (900 m3) of timber, including timber from forests owned by the Mitsui Fudosan Group, will be used
- Offices with an all-wood structure (excluding common spaces) will be realized on the upper floors, where timber is to be used for the main structural elements—floors, walls, columns, and beams
- Timber will also be proactively used for interior and finishing material, creating office spaces where workers can feel close to nature, while working in the city center
- Proactive use of timber and existing piles is expected to reduce CO2 emissions during construction by approximately 25%
- Expected to be the first office building in Tokyo with a total floor area of over approximately 107,639 ft2 (10,000 m2) to obtain Nearly ZEB certification for its office spaces
Tokyo, Japan, November 4, 2025 - Mitsui Fudosan Co., Ltd., a leading global real estate company headquartered in Tokyo, announced today that it has begun construction work for the Nihonbashi Honcho 1-chome District 5 Project (tentative name) (hereafter, “the Project”) on November 1, 2025.
The Project is located in Tokyo’s Nihonbashi—one of Mitsui Fudosan’s key areas for promoting neighborhood creation that expands sustainable and prosperous environments—along Edo Sakura-dori near COREDO Muromachi 1, 2, and 3. This will be the Company’s second hybrid timber rental office building, following Nihonbashi Honcho Mitsui Building &forest. In collaboration with Yamashita Sekkei Inc., which has strengths in advanced timber construction, and Obayashi Corporation, which has a proven track record in constructing various types of timber buildings including all-wood structures, the Project is scheduled for completion in February 2028.
By taking on the challenge of building a timber rental office building that includes timber from forests owned by the Mitsui Fudosan Group, the Company aims to promote urban timber construction and contribute to a sustainable forest cycle.
Perspective drawing of the completed exterior
Perspective drawing of the completed entrance hall
Perspective drawing of the office space (upper floor)
■Background and Significance of the Project
Under its declaration of coexistence with the environment in neighborhood creation, “& EARTH for Nature,” Mitsui Fudosan sees the environment as a “Holistic Environment” blending nature, people, and community into a cohesive whole, and is promoting neighborhood creation that expands sustainable and prosperous “Holistic Environments.” As one aspect of these activities, the Group owns approximately 5,000 hectares (equivalent in area to approx. 1,063 Tokyo Domes) of forest in Hokkaido and is implementing an ongoing cycle of creating “never-ending forests” through sustainable forest management, which involves the steps of planting, cultivating, and using.
The Project represents the Mitsui Fudosan Group’s second hybrid timber rental office building and it aims to promote the circulation of natural resources, which is one of the key issues addressed in “& EARTH for Nature.” As the Japanese forestry industry faces the difficulty of utilizing timber that has been systematically harvested with the arrival of optimal harvesting season, and timber thinned as part of forest maintenance, the Project will use approximately 31,783 ft3 (900 m3) of domestic timber for structural material, including about 1,412 ft3 (40 m3) from forests owned by the Mitsui Fudosan Group.
Declaration of Coexistence with the Environment in Neighborhood Creation “& EARTH for Nature”
Mitsui Fudosan Group’s creation of “never-ending forests
■Project Features
1. Hybrid timber office with partially all-wood construction
On the upper floors (8th to 11th), timber will be used for the main structural elements—floors, walls, columns, and beams—creating office spaces with an all-wood structure*1. On the lower floors (2nd to 7th), timber earthquake-resistant walls will also be used in some of the main structural elements. By proactively incorporating timber throughout the building in this way, more than approximately 31,783 ft3 (900 m3) of timber will be used, fixing approximately 660 tons of CO2 while also helping to make the whole building more lightweight and structurally efficient.
*1 Upper floors only. Excluding common spaces
Structural concept diagram (overall)
Structural concept diagram (upper floors / 9th floor plan)
—Timber Construction Technologies and Materials Used on the Upper Floors—
- Japan’s first application of Mitsui Home’s proprietary timber construction technology “MOCX WALL,” modified for office use
The timber load-bearing wall “MOCX WALL,” originally developed by Mitsui Home Co., Ltd. for use in wooden housing, has been modified for use in timber offices with high floor heights, and the Project will mark the first case of its use in Japan. - Use large-diameter sawn timber (from logs with a top-end diameter of approximately 11 inches (30 cm) or more)
Some columns use sawn timber from large-diameter trees without processing it into laminated material, making use of wood that has previously had limited opportunities for use.*3 - Active use of standard commercial timber to streamline the processing of timber used
To streamline timber processing, standard commercial timber is actively used. For example, commercially available laminated material (120×450) is used for small beams.
- 2 CLT: Cross-Laminated Timber. A wood-based material in which laminae are laminated and bonded in layers so that their grain runs at right angles to adjacent layers
- 3 Laminated material: A wood-based material in which laminae are laminated and bonded in layers so that their grain runs in the same direction. Large-diameter sawn timber: Timber with a large cross-sectional area, directly cut from logs with a top-end diameter of approximately 11 inches (30 cm) or more
The Project will use timber extensively for interior and finishing material, with window-side areas in dedicated spaces allowing direct contact with wood, creating office spaces where workers can feel close to nature, while working in the city center. The Project will create a next-generation office that workers will want to go to by combining high environmental performance with comfort.
Perspective drawing of the completed north-side exterior
Perspective drawing of the office space (lower floor)
2． Pursuing a high level of environmental performance during construction and operation
(1) Expected to be the first office building in Tokyo with a total floor area of over approximately 107,639 ft2
(10,000 m2) to obtain Nearly ZEB certification for its office spaces
The Project’s office building is expected to be the first office building in Tokyo with a total floor area of over approximately 107,639 ft2 (10,000 m2) to obtain Nearly ZEB certification for its office spaces, reducing energy consumption by 75% compared with the standard reference value.
To achieve high environmental performance during building operation, the Project implements a building plan with low environmental impact while introducing highly efficient equipment to promote energy savings. Compared with the standard reference value for the entire building, energy consumption is expected to be reduced by 44% for air conditioning and 26% for lighting.
Breakdown of energy savings and energy creation
| Air conditioning | -44% |
|---|---|
| Lighting | -26% |
| Solar | -4% |
| Other | -1% |
(2) Estimated to reduce CO2 emissions during construction by approximately 25%
By proactively using timber and reusing existing piles from the previous building, the Project is expected to reduce CO2 emissions during building construction of the framing by approximately 25% compared with a typical steel-frame office building of the same scale.*4
CO2 emissions reduction
*4 The amount of carbon storage is calculated based on the Forestry Agency’s “Guidelines for Labeling of Carbon Storage Amounts for Wood Used in Buildings”
Project Overview
| Project name | Nihonbashi Honcho 1-chome District 5 Project (tentative name) |
|---|---|
| Location | Nihonbashi Honcho 1-chome-5, Chuo-ku, Tokyo |
| Site area | Approx. 21,527 ft2 (approx. 2,000 m2) |
| Total floor area | Approx. 193,750 ft2 (approx. 18,000 m2) |
| Structure | Steel frame construction, timber construction, partial SRC construction |
| Main use | Offices, shops, etc. |
| Number of floors / Height | 11 floors above ground and 1 floor below ground / Approx. 183 ft (approx. 56 m) |
| Architect/Builder | Yamashita Sekkei Inc. / Obayashi Corporation |
| Building completion | Scheduled for the end of February 2028 |
* Subject to change depending on the status of considerations going forward.
Location Map
■Sustainability in the Mitsui Fudosan Group
Based on the meaning of its “& mark,” “to generate new value with society through cooperation, coexistence and co-creation, we forge ahead, innovating,” the Mitsui Fudosan Group views the “creation of social value” and the “creation of economic value” as two wheels of a cart. Accordingly, we believe that the creation of social value leads to the creation of economic value, and that this economic value then creates even greater social value.
Moreover, we identified six Group Materiality priority issues when formulating our new management philosophy in April 2024. These Group Materiality priority issues are (1) Contribute to industrial competitiveness, (2) Coexist with the environment, (3) Health and Vitality, (4) Safety and security, (5) Diversity and inclusion, and (6) Compliance and governance. The Mitsui Fudosan Group will work to address each of the materialities through its core business activities and contribute to the promotion of sustainability.
(References)
・ Group Management Philosophy and Long-Term Vision
https://www.mitsuifudosan.co.jp/english/corporate/innovation2030/
・ Group Materiality
https://www.mitsuifudosan.co.jp/english/esg_csr/approach/materiality/
・ & EARTH for Nature
https://www.mitsuifudosan.co.jp/english/business/development/earth/for-nature/
