Institutions affected are Hyakujushi Bank, Joyo Bank, which is part of Mebuki Financial Group and Yamaguchi Bank under Yamaguchi Financial Group, the report said.

Separately, Lawson Bank - operated by convenience store chain Lawson - tweeted the bank is experiencing system failures and their services have been suspended.

Mizuho Financial Group's main banking unit Mizuho Bank has had major system failures several times, prompting the group to name new chief executive earlier this year.

(Reporting by Junko Fujita; Editing by Lincoln Feast.)