NTT DoCoMo declines basic usage fee against next year from other companies

According to the Nihon Keizai Shimbun news report, it seems that NTT DoCoMo intends to lower basic usage fee against au and SoftBank Mobile etc.

Although each company is undergoing intense fight by introducing installment sales and lowering the basic royalty fee, does NTT Docomo, the largest in the industry cut prices, will it trigger other companies to take further countermeasures?

Details are as below.
DoCoMo mobile basic fee price reduction main plan, competing against au Mobile - latest news: IT-PLUS

According to this article, NTT DoCoMo released "Fami club MAX 50" for 2-year contract to "Type SS Value" out of "Value Plan" which lowered calling charges instead of raising terminal price by eliminating sales incentives from July It is said that the basic royalties of 1050 yen will be lowered to 980 yen when combining them.

As a result, au plans to install a fee plan "Plan SS simple" with a charge of 1050 yen newly introduced at the same time as installment sales on June 10 and SoftBank Mobile user calls free except for some time zones It is said that "White Plan" will line up with basic usage fee. Please keep in mind that the charge of 1050 yen for free calls remains.

Three major companies are now in line, but will companies that come up with additional countermeasures come out? I would like to pay attention to future trends.