The Ministry of Internal Affairs and Communications has approved the allocation of spectrum after determining that the companies' applications met the conditions of the allocation, the Nikkei Asian Review reported.
The four companies plan to invest heavily in 5G, spending a combined 1.6 trillion yen ($14.4 billion) over the next five years. Docomo is planning the largest spend, with goals to invest at least 795 billion yen in 5G over this time.
The four plan to commence commercial 5G services in 2020, with KDDI and SoftBank planning to commence advertising for its services in March.
Rakuten Mobile, Japan's upcoming newest market entrant, meanwhile plans to commence 4G services in October 2019 and 5G services in June 2020.
The conditions for the allocation of spectrum included commitments to commence services in every prefecture of the nation within two years, and set up 5G base stations in at least half the country within five years.
According to the report, Docomo and KDDI are each targeting more than 90% 5G population coverage by the end of the five years, while SoftBank is targeting 64% coverage while Rakuten is aiming for 56%.