Mizuho Financial Group Inc. said Monday it will carry out a bold integration aimed at unifying its core banking units — Mizuho Bank and Mizuho Corporate Bank — in the future following the massive disruption to its computer system in March.

Mizuho Bank President Satoru Nishibori will step down June 20 to take responsibility for the computer system glitch, Takashi Tsukamoto, president of Mizuho Financial, said at a news conference.

Nishibori will be replaced by Tsukamoto, who will concurrently serve as chairman of Mizuo Financial, while Mizuho Corporate Bank President Yasuhiro Sato will become president of the holding company.

The consolidation of operations is aimed at creating an effective "one bank" system through the integration of computer systems and personnel management within the group, which will pave the way for the merger of the megabank's two core banks.

Mizuho Bank serves retail clients and small businesses, while Mizuho Corporate caters to big companies and overseas corporate clients.

Mizuho says the computer system trouble, which came to light March 15, was triggered by donation transfer requests overwhelming Mizuho Bank's processing capacity after the March 11 quake, stalling salary transfers, crippling ATMs and creating a backlog of up to 1.16 million unprocessed transactions.

The group also experienced a major computer glitch in 2002 and was slapped with a business improvement order by the Financial Services Agency.

Mizuho Financial Group, the nation's second-biggest megabank in terms of assets, is a product of the merger of three major commercial banks -Dai-Ichi Kangyo, Fuji and the Industrial Bank of Japan.

Tsukamoto, the current head of Mizhuho Financial, is from Dai-Ichi Kangyo. Sato, who heads Mizuho Corporate, is from IBJ.