Last August, Chief Cabinet Secretary Yoshihide Suga dropped a bombshell remark that rattled Japan's mobile phone industry: "There is room to lower people's smartphone bills by around 40 percent."

In the wake of the remarks by the government's top spokesman, a bill aimed at facilitating competition among the top three carriers was deliberated and passed by the Diet last week.

On top of this, the industry expects to see Rakuten Inc. make an attempt to become Japan's fourth major carrier in October, challenging NTT Docomo Inc., KDDI Corp. and SoftBank Corp.