NTT Mobile Communications Network Inc. will invest some 1 billion yen in an online bank to be set up by Sakura Bank this summer, NTT DoCoMo officials said Monday.

The mobile phone subsidiary of Nippon Telegraph and Telephone Corp. plans to take a 5 percent stake in the Internet-based bank, called Japan Net Bank.

The new bank is to be established as early as this summer, and Sakura Bank will provide more than half of the online bank's initial capital of about 20 billion yen, the officials said.