Japan mobile operators KDDI and SoftBank solidified plans to work together on the deployment of 5G infrastructure targeted at rural areas of the country. The move comes on the heels of Japan’s largest operator NTT DoCoMo launching commercial 5G services and just ahead of new entrant Rakuten Mobile’s push into the market.

Japan’s second- and third-largest mobile operators will share base stations used to transmit the 5G signals in rural areas. They will also collaborate on the construction design and management work for those 5G base stations.

Each operator will split ownership and provide a “co-CEO” to the joint venture, which has an initial budget of $4.7 million. The joint venture also builds on an agreement the two operators announced last July that was focused on initial network trials.

Published reports have indicated that KDDI and SoftBank both launched 5G services late last month. Both were targeted initially at just a handful of urban markets.

The KDDI-SoftBank joint venture plays into Japan’s 5G spectrum plans. The country has set aside spectrum in the 3.7 GHz and 28 GHz bands to support 5G services, both of which are higher spectrum bands that what Japan’s carrier’s use for their current 4G LTE services. This in turn will require operators to deploy more base stations to gain equal coverage, which is financially challenging in rural areas where there are fewer customers “paying” for service.

Japan’s four mobile operators have pledged to invest a combined $14.4 billion in their networks through 2024. DoCoMo, which is the country’s largest operator, is carrying the largest burden of a promised $7.1 billion in investments. KDDI said it would invest at least $4.16 billion, while SoftBank pledged $1.84 billion in investments, and Rakuten has planned $1.73 billion in spending.

DoCoMo launched its commercial 5G service late last month. The launch included 500 base stations covering around 150 “locations” around the country with plans to expand to all prefectures by June. The expansion will then hit 500 cities over the next year and scale up to 20,000 base stations over the next two years.

Rakuten has said it was on track to launch its initial 4G LTE service on April 8, with its 5G network to follow later this year. The service will rely on a combination of the carrier’s own equipment that relies heavily on virtualized infrastructure and a roaming agreement with KDDI that runs through March 2026.

The 5G launch timing was initially set to align with the 2020 Summer Olympics in Tokyo that were scheduled to begin July 24. However, the event has been postponed until next year due to the ongoing COVID-19 virus outbreak.