Hiroshima Bank began Monday using a system it is sharing with Bank of Fukuoka, making the two the first regional banks to entirely share a backbone system.
The two banks agreed to unify their systems in August 1999 in a bid to save costs.
The shared system was launched without merging operations or integrating management, and Bank of Fukuoka began using it last January.
"We have room in the system, so we would like to call on other banks to join us," said Sho Takahashi, president of Hiroshima Bank.
Other banks are getting ready to launch similar systems.
Michinoku Bank of Aomori Prefecture, San-in Godo Bank of Shimane Prefecture and Higo Bank of Kumamoto Prefecture have planned to do the same. Higo went ahead using its shared system Sunday.
Eighteenth Bank, based in Nagasaki Prefecture, Bank of Saga, based in Saga Prefecture, and the Chikuho Bank, headquartered in Fukuoka Prefecture, are also expected to start up a shared system in 2006.