The yen will weaken as the Government Pension Investment Fund moves to become more competitive, according to Takatoshi Ito, who led a panel advising the Abe administration on overhauling the system.

The GPIF, the world's biggest retirement fund and which invested about 55 percent of its ¥126.6 trillion in assets under management in Japanese bonds as of March, may buy more equities after a strategy review ends, the former Finance Ministry official said.

The review, which may be completed in the next few months, also covers governance.