The massive Government Pension Investment Fund must be ready to buy more stocks should Prime Minister Shinzo Abe's policies succeed in reviving the economy, according to its head of research.

"We may see structural reform and Japan as we know it may change," Tokihiko Shimizu, director general of the research department at the ¥130 trillion fund, said in an interview Wednesday in Tokyo. "If we subscribe to that view, we must commit to different investment behavior than just trading within a boxed range. This is particularly true for local shares."

While Japanese equity rallies faltered quickly in the past, this one may be longer-lasting, Shimizu said.