NTT DoCoMo staff prepare for the company's 2011 summer model press preview in Tokyo. Japan's top mobile carrier NTT DoCoMo said it will make Tower Records Japan a subsidiary to enhance its online sales of CDs and DVDs.

Japan's top mobile carrier NTT DoCoMo said Monday it will make Tower Records Japan a subsidiary to enhance its online sales of CDs and DVDs.

DoCoMo, which already holds 42.1 percent of the music store chain, will increase its stake to 50.3 percent by mid-July for an undisclosed price.

"By establishing Tower Records Japan as a subsidiary, expects to capitalise on the envisioned growth of e-commerce triggered by the proliferation of smartphones and tablets," the mobile firm said in a statement.

Tower Records operates 89 stores in Japan, in addition to an online music shop.