Mitsui Fudosan and Partners To Develop Japan's First Underground Data Center Using an Existing Tunnel

Mitsui Fudosan, Kumagai Gumi and Getworks announced on October 6, 2026, that they will begin developing an underground data center using an existing tunnel in Kobe. Operations are scheduled to begin at the end of 2027, and it will be Japan's first commercial data center business to use an existing tunnel.

The project will use approximately 3 km of a 14.5-km tunnel for a belt conveyor that the City of Kobe used until September 2005 to transport soil for land development. Container-type data center equipment will be installed inside the tunnel at a depth of approximately 40 m or more below ground, with the aim of operating a data center with a maximum power receiving capacity of 20 MW.

The project will respond to growing demand for GPU servers driven by the spread of generative AI, as well as demand for infrastructure that securely stores and operates critical data. By taking advantage of the existing tunnel's cool temperature, which remains at 15 to 20 degrees Celsius year-round, its seismic resistance and the physical security afforded by limited external access, the companies also aim to shorten the time to commercialization.

Getworks will handle operations. The company has been building container-type data centers since 2013 and had built a cumulative total of 380 units as of September 2026. Construction is scheduled to be handled by Kumagai Gumi, which was also involved in building the tunnel, and Pacific Consultants will participate as a cooperating company.

Mitsui Fudosan positions the project as the first step toward a model that makes use of idle underground spaces nationwide, and aims to develop underground data centers at multiple locations using tunnels, former mine sites and other spaces.