Cybersecurity breaches in Japanese companies

Multiple Japanese organizations have reported various cybersecurity incidents involving unauthorized access and data leaks.

In late August 2026, several companies disclosed breaches affecting large numbers of individuals. Kaga Solnet reported that personal information for approximately 165,587 customers was leaked due to an attack spanning from late 2021 to early 2026. Other reported incidents included unauthorized access to NTT Smart Connect’s Smile Server rental service, the potential viewing of 6,000 staff and partner records via Kyodo News reports, and vulnerabilities exploited across 78 websites managed by Gakken Medical Support.

Following these reports, Kota Co., Ltd. disclosed that a March 2026 cyberattack may have compromised the personal information of approximately 109,000 shareholders, users, and partners. Additionally, Meitetsu Kyosho Co., Ltd. reported a ransomware attack targeting its ‘Kariteko’ car-sharing service, which potentially exposed names, addresses, dates of birth, contact details, driver’s license information, and credit card data for current and former members.