Companies across Japan have a new name in their top 10 shareholder lists: the world's largest pension fund.

The ¥134 trillion Government Pension Investment Fund is the top owner of Mitsubishi UFJ Financial Group Inc., Honda Motor Co. and at least 119 other Tokyo-listed firms, according to Bloomberg analysis after GPIF unveiled its individual investments for the first time last month. It is the second-biggest holder in Toyota Motor Corp. with a 5.5 percent stake in Japan's largest company. At the latest reckoning, the retirement savings manager owns about 5.8 percent of the stock market.

"Its scale and presence is huge," said Yoshinori Shigemi, a global market strategist in Tokyo at JPMorgan Asset Management Ltd. "Now that it has finished its big shift to equities, it can start being more selective about which companies it buys."