# Data breaches in Japanese companies > Live situation record from CLSTR: https://clstr.news/situations/data-breaches-in-japanese-companies > Updated: 2026-09-28T02:01:00.000Z. Sources: 9. Developments: 2. In late August 2026, several Japanese companies reported data breaches involving unauthorized system access. SKI Management reported that an employee fell victim to a support fraud scam, leading to the potential deletion of approximately 4,000 files containing customer personal data. Mitsui Fudosan also reported unauthorized access that may have compromised the information of up to 55,000 individuals, including employees and external stakeholders. By late September, the number of reported incidents increased. Tokyo Metro identified a potential breach affecting approximately 59,000 loyalty program email addresses. Japan Post suspended its international mail inquiry web service following the discovery of potential unauthorized access. Other companies reported significant impacts: Nippon Rent-A-Car noted potential compromises to 41 members, while the car-sharing service Times Car experienced a breach affecting approximately 6.6 million accounts. Additionally, Seicomart disclosed that unauthorized access to its app servers may have affected approximately 570,000 club member accounts, potentially exposing names, genders, dates of birth, addresses, and phone numbers. ## Timeline ### 2026-09-28: Japan companies report multiple data breaches via unauthorized access Several Japanese companies, including Tokyo Metro, Japan Post, and Seicomart, have reported unauthorized access to their systems, potentially compromising millions of user accounts and personal data. 8 sources. https://clstr.news/cluster/tokyo-metro-reports-potential-leak-of-59000-member-email-addresses ### 2026-08-31: Japanese companies SKI Management and Mitsui Fudosan report data breaches SKI Management and Mitsui Fudosan report potential data breaches in Japan. SKI Management faced support fraud affecting 4,000 files, while Mitsui Fudosan reported unauthorized access affecting up to 55,000 data 2 sources. https://clstr.news/cluster/japanese-companies-ski-management-and-mitsui-fudosan-report-data-breaches --- Cite as: Data breaches in Japanese companies. CLSTR, https://clstr.news/situations/data-breaches-in-japanese-companies