Strategy to Bolster Japan's International Network Connections

7 September 2023

Japanese version: 1 July 2023

Kei Imamura
Digital Innovation Division


  • Japan is a hub for data flow between the US and Asia
  • Investors are on the hunt for a country to host their new data centers in Asia
  • Data center positioning hinges on two factors: power sources and dispersion of sites

Asia’s hub for submarine communications cables

Undersea cables carrying over 99 percent of the communications traffic between Japan and the rest of the world are a vital basic infrastructure and now also have economic-security implications.

Standing shoulder-to-shoulder with Hong Kong and Singapore, Japan makes its presence felt as a data-transit hub*. Over 20 submarine cables connect directly to the country, mostly trunks between it and the US or other Asian countries, for which it also provides interconnectivity1. Of the latter cables, some connect to Hong Kong and Singapore, whence they cross the Malacca Straight to link to points beyond in Central Asia and the Middle East.
[Figure] Principal cables on the seabeds around Japan
Principal cables on the seabeds around Japan
Source: Mitsubishi Research Institute from TeleGeography's Submarine Cable Map

*Hub : A massive transit point in a communications network that receives and redistributes data

Content providers now lay their own submarine cables

Data moving to or from massive-volume data centers2 run by content providers like Google and Meta accounted for some 64 percent of traffic flowing through the world’s subsea cables in 2019. According to estimates, this holds for data travelling between the US and Japan as well, and it is a factor behind moves by content providers to lay their own networks of undersea cables, separate from those of communications vendors.

Chinese companies, too, are more and more frequently involved in projects to lay intra-Asian submarine cables, reflecting how many have landing points in China (chiefly Hong Kong).

For economic security, marine cable connections should be made multi-route to enhance redundancy, and whenever possible laid by domestic or friendly-country entities. This necessitates more-strategically assembled consortiums of multiple vendors to guarantee optimal cable routings. A project to link Japan with North America and Northern Europe via the Arctic Ocean is already afoot, and it can be characterized as an instance of such multi-routing.

Deep connections between data centers and submarine cables

Content providers like Google and Meta embarking on laying their own undersea cables is an indicator of the advantages of controlling their services with their own cable systems. Further, there’s much to be gained from considering together the siting of data centers and cable landing-points. For instance, most cables landing in Japan connect to Internet exchanges in Tokyo or Osaka—which means that over 80 percent of Japan’s data centers are concentrated in the outskirts of Tokyo and Osaka.

A further issue that dogs data centers is that of power. For example, Singapore—typical of areas with high concentrations of data centers in Asia—has begun limiting their new construction because of problems like their burden on electricity supply. Data center siting is also influenced by many other factors, including other communications infrastructure, energy costs, the availability of renewable energy, natural disaster risk, and political stability.

Hong Kong also has a high concentration of data centers, but the environment for doing business has changed since its return to China. With the search on for alternatives, Japan, Taiwan, and Indonesia have emerged as leading candidates, but as things stand each entails its own set of advantages and disadvantages. To enhance Japan’s advantages while making the most of its being a data traffic hub, the country needs to bring users and all other stakeholders together to strategically address two principal issues: power and dispersion.

Ensuring a suitable energy landscape the priority

As gleaned from the Singaporean situation, data-center siting is closely tied to the energy landscape. This relationship makes clear the move globally to erect data centers in countries with low power costs.

Given the now-key social demand that data centers utilize renewable energy, access to such sources is also a determining factor when looking for suitable sites, and sometimes a consideration for dealing with skyrocketing fossil-fuel prices. This all makes huge hurdles out of Japan’s comparatively high electricity costs and limited number of vendors able to supply renewable power in the volumes data centers require.

Spreading data centers across regions reduces risk from natural disasters

Natural disasters pose a huge risk: Japan is without a doubt one of the world’s most earthquake-prone countries. No one can afford to be unprepared for quakes at and exceeding magnitude-7 levels, especially given the Tokyo area’s vulnerability to a direct-hit and the imminence of a massive event facing the western region of Japan.

Dispersing data facilities to sites outside of urban centers brings big advantages from the energy perspective3 as well: Whereas sourcing renewable energy for them can be problematic in urban settings, the countryside provides more numerous possibilities. Though costs often surpass demand right now for data centers in the provinces, the imminent data explosion, sparked by generative-AI uptake and other similar developments, could well create demand for siting data centers in out-of-the-way places.

Author profile


Kei Imamura

Digital Innovation Division

Joined Mitsubishi Research Institute in 1997. He has been and continues to be involved in numerous studies and policy-recommendation projects in ITC fields from building security, open data, and open governance to digitalization of government services, as well as infrastructure such as data centers and communications, both wired and wireless.