The vast conglomerate said it was now seeking a combined 3.2 billion yen (USD 27 million) from five former top managers including three presidents, up from an earlier claim for a total of 300 million yen.
Toshiba, which sells everything from rice cookers to nuclear reactors, said it boosted the size of its lawsuit after Japan's market watchdog last month slapped the 140-year-old company with a record USD 60 million fine over the affair.
Last year a company-hired panel found the firm had inflated profits by about USD 1.2 billion since the 2008 global financial crisis.
It found top executives had pressured underlings systematically to inflate profit figures to hide poor results.
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Toshiba's business was dented by the global downturn, while the 2011 Fukushima disaster killed off demand for atomic power at home in a big blow to the firm's key nuclear division.
Itv was one of the most damaging accounting scandals to hit Japan in recent years. The case forced an incumbent president and seven other top executives to resign last year and hammered the company's share price.
Known for its televisions and electronics, including the world's first laptop personal computer and DVD player, Toshiba has a range of other operations including power transmission and medical equipment.
Last month the company rolled out a wide-ranging restructuring which included thousands of job cuts, as it warned it would book a record USD 4.5 billion annual loss.
The company has about 200,000 employees globally.