The umbrella body for about 1,400 corporate pension funds filed a suit Thursday against Seibu Railway Co., its parent Kokudo Corp. and Yoshiaki Tsutsumi, the effective owner of the Seibu group, demanding 4.26 billion yen in damages for the investment loss it incurred due to the falsification of Seibu's financial statements.

The Pension Fund Association is demanding the three parties compensate it for losses stemming from a dive in the Seibu share price since Oct. 13 in the suit filed with the Tokyo District Court.

"Seibu Railway has severely undermined investors' confidence in the securities markets," the association said. "In making a restart, the company should compensate in a responsible manner for the damages it inflicted on its shareholders on the basis of its illegal activities."