A Government Pension Investment Fund (GPIF) official confirmed a Wall Street Journal report on Thursday which said a lawsuit by Japan Trustee Services Bank against Toshiba, filed on May 6 and previously reported by other media, had been on its behalf.
A hearing is set for June 21, the official said.
Toshiba's shares have been recovering in recent months but are still down around 40 percent from early April 2015 when Toshiba first disclosed accounting irregularities.
GPIF, the world's biggest pension fund, decided in 2014 to double its allocation for share holdings in its trillion-dollar portfolio, while slashing investments in low-yielding government bonds, in a bid for greater returns and risk.
It has also said it could consider corporate governance, in addition to investor returns, when deciding on stock investments, raising expectations it could play a bigger role in improving corporate governance in Japan.
Toshiba was not immediately available for comment.
An investigation last year found widespread accounting errors throughout the laptops-to-nuclear conglomerate, and blamed a corporate culture in which employees found it difficult to question their superiors.