Another example for the pessimists is Toyo Tire, which said for the second time this year it had uncovered fake data. The company's previous chairman and president announced their resignations in June, months after the company said it sold substandard earthquake-resistant components for buildings.
In addition, Toyo Tire in 2007 admitted to falsifying data for fire-resistance. The company set up a quality assurance center that year to ensure such problems weren't repeated.
“I can imagine investors are feeling rather disappointed, and investment managers are asking why this happened,” said Temple University's Mr. Kingston. “We've discovered the brand Japan, based on exceptionally high-quality products, may not be quite what it seems.”
Japan is ranked first in the world for supplier quality, according to a 2014-15 report from the World Economic Forum.
Optimists argue that Mr. Abe's effort to improve corporate governance is taking hold and the surge in corporate disclosures reflects progress. The new code took effect in June, and companies are supposed to meet the new government standards or explain why they failed.
“The fact that now these issues are coming out and being discussed in the open is actually a healthy sign of cleansing,” said Jesper Koll, chief executive officer of WisdomTree Japan. “It's actually showing that these changes in corporate governance are for real, that transparency and accountability is being taken very, very seriously.”
The pressure for disclosing problems may grow as Mr. Abe and groups such as The American Chamber of Commerce in Japan press for tighter compliance.
“Once something starts here, it really has a life of its own, and then it becomes stricter than other countries,” said Edwin Merner, president of Atlantis Investment Research Corp. in Tokyo.
Some people point to the cultural problems Japan still faces in encouraging employees to come forward about cover-ups.
“The biggest problem in Japanese corporate governance is companies' rigid respect for hierarchy and that one should never go over his boss's head or he will suffer retaliation,” Mr. Benes said. “This keeps bad news from rising.”
Contributing to this Bloomberg News report were Kiyotaka Matsuda and Katsuyo Kuwako in Tokyo.