Japan's transport ministry has uncovered that the country's five major Japanese automakers -- Toyota, Honda Motor, Mazda, Yamaha Motor, and Suzuki Motor -- have been implicated in illegal fraudulent practices during their mass production certification applications.

Commenting on the scandal, Japanese auto industry journalist Kazuo Shimizu said the image of Japanese brands was tarnished and questioned why such incidents have occurred in a country known for its rigorous quality standards.

"The question is, why are there so many such incidents in Japan? Japanese automobile manufacturers have had an international reputation for being extremely reliable and high-quality. However, the image of Japanese brands is now being tarnished. This is the worst outcome of these recent scandals," Shimizu said.

Toyota claimed that some of the tests were conducted under stricter conditions than required. However, the transport ministry believes Toyota Motor's misconduct on vehicle certification may violate domestic standards and UN vehicle regulations.

"I think it's presumptuous of the engineers to believe that because they conducted stricter tests than required, they don't need to perform the certification tests. They assumed it was acceptable to pass the simple certification tests because they were doing something more difficult. Instead of conducting proper tests, they replaced the certification test data with results from their stricter tests, resulting in false data," said Kazuo.

The news severely affects car dealers, with customers reconsidering their decisions about purchasing new or used cars, fearing more irregularities might emerge.

"Many of my customers have had second thoughts about purchasing cars with data falsification. Even those who planned to buy a car with their next bonus are now cautious and may delay their purchase, unsure which model would be safe to buy," said Ali Narita, president of the Base Auto.

The Ministry of Transport conducted on-site inspections at each company regarding misconduct in model certifications. Officials said the ministry would decide on administrative action based on the Road Transport Vehicle Law.

Last year, Daihatsu Motor was found to have falsified crash test results, sparking criticism of its parent company, Toyota Motor.

This issue dates back to 2016, starting with Mitsubishi Motors' falsifying fuel efficiency data. Since then, carmakers such as Nissan and Subaru have been reported for falsifying inspection data almost annually.