"We view our business with startups as crucial, because we want to drive changes in Japan," Masahiko Kato, the new chief executive of Mizuho Bank, told Reuters in an interview.

Japan has fewer than a dozen unicorns - startups with a valuation in excess of $1 billion - compared with hundreds in the United States.

Kato said the banking group had recently built an organizational framework to support startups from early stages through to listings. This included allocating specialist bankers, because assessment of startups required different expertise.

The group, which includes Mizuho Securities, aims at doubling revenue from financing and advising startups within two years, Kato said, without giving a specific number.

The bank's setting of the target comes as the government plans to encourage funding of startups and venture capital. It could use the Government Pension Investment Fund, the world's largest pension fund, in helping to finance startups.

(Reporting by Makiko Yamazaki and Yuki Nitta; Editing by Bradley Perrett)

By Makiko Yamazaki and Yuki Nitta