Japan’s Data Leaks Mount as Experts Warn of AI-Assisted Cyberattacks

Japanese companies and local governments have reported a growing number of data breaches, prompting cybersecurity experts to warn that artificial intelligence is making it easier for attackers to identify system vulnerabilities.

Japanese companies face growing cybersecurity concerns as major data breaches expose millions of records.

According to Trend Micro Inc., companies and local governments in Japan had publicly reported 600 cases of unauthorized access and other cyber-related damage by the end of September 2026.

That was more than 100 cases above the totals recorded over the same period in both 2024 and 2025, putting this year on course to be the worst of the three-year period, according to figures cited in a report by Ikuko Ando for The Mainichi.

The breaches have affected businesses holding substantial amounts of personal information.

In late September, car-sharing service Times Car disclosed unauthorized access that reportedly exposed approximately 6.6 million pieces of personal information, including images of driver’s licenses.

The exposure raised concerns that the information could be misused for identity theft or impersonation, particularly because driver’s licenses are commonly used to verify identities during financial and other transactions.

Several other major incidents were disclosed in October.

East Japan Railway Co. (JR East) said information associated with approximately 6.09 million accounts on its Ekinet reservation service and group company Viewcard Co. may have been compromised.

Bookoff Group Holdings Ltd. reported a possible breach affecting up to 6.43 million customer records, while Adventure Inc., the operator of the Skyticket travel booking website, reported a potential breach involving approximately 14.64 million sets of personal information.

Cybersecurity specialists have identified the growing misuse of artificial intelligence as one possible factor behind the increase in attacks.

Takayuki Sugiura, representative director of the Japan Hackers Association and a white-hat hacker, said AI had accelerated the process of finding vulnerabilities.

He said the technology had reached a level at which it could be used in cyberattacks and that he had observed an apparent increase in unauthorized access since July.

The concerns underscore the need for organizations to strengthen security monitoring, patch vulnerable systems promptly and review how personal information is stored and protected.

AI can also be used for defensive purposes, so its role in any individual breach must be established through evidence rather than assumed.