[REVISION HISTORY]

Cybersecurity incidents in Japanese companies

Updated 1 time since CLSTR started tracking revisions of this situation.

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2026-09-29 01:31 UTC → 2026-09-29 05:50 UTC · added ~~removed~~

In early September 2026, several Japanese companies reported various cybersecurity incidents. These included ransomware attacks, phishing scams, and unauthorized access. Notable impacts included Logic Vein Co., Ltd., which reported that data belonging to approximately 97,338 individuals may have been compromised, and T&K TOKA Co., Ltd., which suspended some business operations due to ransomware. Later in the month, the Keio Group, including Keio Plaza Hotel and Keio Electric Railway, reported a ransomware attack on its servers. The attack caused system failures in certain business systems, prompting the group to disconnect external networks as a containment measure. While Keio Electric Railway stated that train services were not impacted, investigations into potential data theft and the scope of the attack remained ongoing. On September 26, 2026, Keio Corporation confirmed the ransomware attack targeted its group servers in the early hours of the day. The disruption specifically affected the hospitality sector, including the Keio Plaza Hotel, where reports indicated that payment systems were impacted, potentially causing delays in customer services. While train operations remained unaffected, the company is working with police and external experts to investigate the attack route and determine if any customer or business partner information was accessed. As of the latest reports, no data leaks have been confirmed.

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