A malware infection on an employee’s computer at Nippon Columbia Group Co., Ltd. (NCG) may have exposed approximately 8.724 million customer and employee records associated with Japanese karaoke and restaurant operator Daiichi Kosho.
Daiichi Kosho disclosed the incident on October 8, 2026, stating that the affected computer temporarily stored personal information handled under an outsourcing arrangement. The company has not confirmed that the information was stolen or misused.
NCG identified the malware infection between October 1 and 2 and isolated the computer from its network on October 2. The contractor notified Daiichi Kosho on October 5 after investigating the incident. The investigation into the cause and potential data leakage remains ongoing, according to Daiichi Kosho’s official announcement.
The potentially affected data covers approximately 8.631 million customer records after accounting for about 515,000 duplicate records across brands, alongside 93,000 employee records. Before deduplication, the customer records totalled approximately 9.146 million.
BIG ECHO accounted for approximately 5.558 million customer records, while DK Dining accounted for another 3.462 million before duplicates were removed. Other affected business groups included Karaoke CLUB DAM, MEGA BIG, Banana Club and B-GARAGE, according to figures reported by Japanese technology publication INTERNET Watch.
The personal information potentially involved includes names, gender, dates of birth, email addresses and telephone numbers. Daiichi Kosho said passwords were not included in the identified data. The company also reported that the information alone could not be used to redeem customer loyalty points and that it had not confirmed unauthorized point use.
NCG isolated the affected computer and reset authentication credentials. Daiichi Kosho is investigating the incident’s scope, reviewing its own systems and examining measures to prevent a recurrence. The company has also advised customers to watch for suspicious emails, text messages and phone calls that could use personal details for impersonation or phishing.
On October 9, Daiichi Kosho opened a dedicated customer enquiry hotline at 0120-732-079, available from 10 a.m. to 5 p.m. on weekdays, excluding Japanese public holidays. Customers can also contact the company at incident-desk@dkkaraoke.co.jp, according to its incident response notice.
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