NTT DoCoMo Inc., Japan's largest but slowest-growing mobile-phone operator by customer, said Friday it plans to spend about ¥10 billion to promote a new corporate logo as it seeks to stem a decline in its market share.

"We need to polish the brand and strengthen our connection with users," DoCoMo President Masao Nakamura said at briefing in Tokyo. "We need to listen and respond to customer needs."

Call discounts have failed to help DoCoMo, which has about 50 percent of the nation's mobile-phone market, win more users than KDDI Corp. and Softbank Corp.

DoCoMo added roughly 237,000 customers in the first quarter, fewer than half the gains at either of the two smaller carriers.

DoCoMo, which plans to begin using the new logo in July, said it will give extra battery packs to customers of its faster network who have signed up for at least one year. Disabled customers and subscribers seeking to buy a second phone will get bigger discounts, DoCoMo said.

Separately, DoCoMo is continuing its negotiations with Apple Inc. to offer the iPhone in Japan, Nakamura said.