Yoshitaka Kitao wants to build a financial empire in an area shunned by investors: the downtrodden ranks of Japan's regional banks.

The chief executive officer of SBI Holdings Inc. says he has close to $1 billion to plow into any of the 104 local lenders scattered across Japan, which were described recently by one analyst as an "accident waiting to happen." More than 10 banks have approached the financial conglomerate for investment, Kitao said in an interview, without naming them.

Kitao is betting that his firm, which has shaken up Japan's securities industry by becoming the biggest online brokerage, can help to modernize banks that still rely on costly physical branches to serve ailing rural communities. SBI took its first step last month when it agreed to take a one-third stake in the struggling lender Shimane Bank Ltd.