Neighborhood Gateway to Undergo Renewal
Construction Begins on Tamachi Station West Exit Area Development Project
—Large-scale Mixed-use Project Directly Connecting to JR Tamachi Station and Toei Mita Station—

October 1, 2025
Mitsui Fudosan Co., Ltd.
Morinaga Milk Industry Co., Ltd.
East Japan Railway Company

Key Points of this Press Release

1. Construction has begun on a new landmark property, replacing the former Morinaga Plaza Building in front of Tamachi Station’s west exit.
2. Improvements to the station-front rotary, intersection upgrades, and the construction of new barrier-free subway route will dramatically improve safety and convenience around Tamachi Station and Mita Station.
3. In a prime location directly connected to the west exit deck of Tamachi Station, this mixed-use development project will feature offices, retail facilities, and a startup support hub—all with access to two stations and four railway lines.
4. Enhancing disaster response capabilities for the Tamachi-Mita area through measures such as developing temporary shelter facilities for stranded commuters. Promoting the building’s energy efficiency, with the aim of obtaining ZEB Ready certification for office use.

Tokyo, Japan, October 1, 2025 - Mitsui Fudosan Co., Ltd., Morinaga Milk Industry Co., Ltd., and East Japan Railway Company (“JR East”), announced today that construction on the Tamachi Station West Exit Area Development Project (hereafter, “the Project”) began on October 1, 2025, with the groundbreaking ceremony held today. The Project is scheduled for completion in two phases: the building will be completed by the end of March 2029 in the first phase, and a green plaza will be developed in FY2033 in the second phase.

The Project will bring development, growth, and vibrancy to the Tamachi-Mita area. At the same time, improvements to infrastructure will enhance safety and comfort, and disaster response capabilities, supporting the creation of an advanced and appealing neighborhood.

Rendering of exterior (Route 15 side)

Rendering of the station-front deck plaza

■Neighborhood creation that enhances safety and comfort through extensive infrastructure development around the stations

This development will integrate infrastructure improvements for both the stations and the surrounding neighborhood. At ground level, the transportation plaza will be developed, expanding it from approximately 12,916 ft² (approximately 1,200 m²) to approximately 32,291 ft² (approximately 3,000 m²). This will include widening sidewalks and adding bus and taxi drop-off zones to improve the pedestrian network. Additionally, converting the intersection facing National Route 15 (Daiichi Keihin) into a scramble crossing will enhance safety. Waiting areas will also be expanded to improve comfort. In 2033, a green plaza will be developed to provide a relaxing space for neighborhood and workers.

TAt the second-floor level, plans call for widening the east–west pedestrian walkway in JR Tamachi Station and expanding the deck plaza in front of the station. Measures to ease rush-hour crowding, combined with a new barrier-free route linked to Toei Mita Station, will help create a safer, more secure neighborhood in the Tamachi-Mita area as a whole. The station-front deck plaza is scheduled for development on a scale of approximately 21,527 ft² (approximately 2,000 m²).

Rendering of National Route 15
(conversion to a scramble intersection)

Cross-sectional rendering of the transportation plaza and station-front deck plaza

Rendering of the green plaza
(scheduled for completion in FY2033)

Rendering of the station-front deck plaza
(within the planned site, near the retail facilities)

■Mixed-use development project featuring office and retail facilities accessible via two stations and four railway lines

The Project is a large-scale mixed-use development centered on the former site of the Morinaga Plaza Building in front of Tamachi Station's west exit. It will feature a building with a site area of approximately 0.6 ha and a total floor area of approximately 1,054,863 ft² (approximately 98,000 m²), incorporating offices, retail facilities, and a startup support hub. Through this development, the Project will act as a hub for transportation, industry, and urban vibrancy, undergoing a total transformation alongside the neighborhood as a landmark property in the Tamachi-Mita area.

Cross-Section Map by Use

• Offices (6th–23rd floors) These offices feature some of the largest floor plates in the Tamachi–Mita area at approximately 33,260–35,197 ft² (3,090–3,270 m²) per floor. With direct links to the JR Tamachi Station west exit deck and Toei Mita Station, the site offers excellent access via two stations and four railway lines—providing a highly convenient office space for workers. Morinaga Milk Industry Co., Ltd. also plans to relocate its headquarters to several of the floors.
• Startup Support Hub (4th floor)
  
  The fourth floor is planned to house a startup support hub aimed at nurturing and supporting startups that address various social issues. To foster interaction with major corporations and mega-ventures concentrated in the Tamachi-Mita area and to target mutual business opportunities, ATOMica Inc., a company with strengths in building communities and managing over 50 incubation facilities nationwide, has been selected as the operating partner. Together, efforts will be made to establish an innovation ecosystem throughout the area.
• Retail Facilities (1st–3rd floors)
  
  A retail facility operated by atre Co., Ltd., part of the JR East Group, is scheduled to open on the first to third floors. It will attract shops that enrich the daily lives of office workers and general visitors, bringing even more vibrancy to the Tamachi-Mita area.

■Enhance the City’s BCP Functions by Establishing Temporary Accommodation Facilities for Stranded Commuters. Enhance Energy Efficiency with the Aim of Obtaining “ZEB Ready” Certification for Office Use.

As part of the Project’s contribution to disaster prevention functions in the Tamachi-Mita area, the facility will serve as a temporary shelter for stranded commuters in the event of a disaster and will use signage to disseminating disaster-related information, thereby contributing to the creation of a safe and secure neighborhood. The planned building is designed to provide approximately one week of power supply using medium-pressure gas-powered electricity generation during power outages. Additionally, it will offer an environment capable of supplying power for 72 hours even during simultaneous power and gas outages, supporting the BCP of tenant companies. As part of its environmental initiatives, the building will include both an emergency generator and a cogeneration system that also functions as a regular-use power generator, optimizing the operation of electricity and heat supply. Additionally, the building’s lower floors will incorporate passive design, transforming shared spaces into semi-outdoor areas to enhance ventilation. Through these initiatives, the building’s energy efficiency will be enhanced, with the aim of obtaining ZEB Ready certification for office use.

* A zero energy building (ZEB) is a building that aims for net-zero energy consumption while providing a comfortable indoor environment. “ZEB Ready” means a building using advanced architectural designs targeting ZEB, with an exterior capable of high heat insulation and highly efficient, energy-saving equipment. It is defined as a building that reduces primary energy consumption by 50% or more from standard primary energy consumption, excluding renewable energy.

Map

*The content in this release is based on current plans and may change.