Hiromichi Mizuno, chief investment officer for Japan's ¥169 trillion ($1.5 trillion) Government Pension Investment Fund, Tokyo, ended his stint overseeing the world's largest pension fund Tuesday.
Over the past five years, Mr. Mizuno has been a high-profile proponent on issues such as climate change, environmental, social and governance factors and achieving alignment of interests with external managers.
He also oversaw the fund's move into risk assets from a portfolio that had been dominated by Japanese government bonds.
"During my time at GPIF, I managed to achieve many things, including controversial ones," he said in an email.
Now after five years in the spotlight, Mr. Mizuno said he "would like to take some time to rethink my mission and possible role to play."
A replacement will be appointed by the fund's new president, a spokeswoman said. Masataka Miyazono will take the helm at GPIF on April 1.