The Financial Services Agency and the Bank of Japan started on-site inspections at two Mizuho Financial Group banks Wednesday.
The inspections of Mizuho Bank and Mizuho Corporate Bank follow a series of computer glitches that hobbled money transfers and automated teller machine operations at the two banks after their April 1 launch under Mizuho Holdings Inc.
The glitches caused some customers to be double-billed for utilities charges, while ATMs malfunctioned and other delays arose.
Four FSA inspectors, including computer experts, arrived at Mizuho Holdings' headquarters in Tokyo at around 9 a.m., FSA officials said.
The inspectors will investigate the causes of the fiasco, the banks' preparedness before the merger, and measures taken after the problems came to light.
Mizuho Bank, which primarily serves individual customers, is being inspected by the FSA. The BOJ is inspecting Mizuho Corporate Bank, which serves major corporate clients.
The inspections began a day after the financial giant submitted its second report to regulators over the computer fiasco. The inspections are expected to last nearly a month, according to financial regulators.
The FSA may give the group a business improvement order.
Based on the results of the inspections, the FSA is expected to issue a business improvement order to the Mizuho group as early as June.
The Mizuho group itself plans to draw up steps to prevent a recurrence. It will also dole out punitive measures once the results of the inspections are in.