Sales rose 6.2 percent to 3.37 trillion yen in the period, while operating profit fell 5.6 percent to 702.2 billion yen, the company said.
NTT DoCoMo left its full-year forecast unchanged, projecting net profit at 507 billion yen and operating profit at 820 billion yen on sales of 4.52 trillion yen for the year to March.
But it warned that "competition in Japan's mobile telecommunications market is expected to remain intense in such areas as acquisition of subscribers and further improvement of service offerings".
In October, NTT DoCoMo cut its full-year profit forecast due to rising infrastructure costs.
DoCoMo is locked in a fierce competition with domestic rivals KDDI and Softbank, both of which offer Apple's iPhone.
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