2026 Monogatari (Yakiniku King) — app member system breach; 10,788,963 records
Data compromised
10,788,963 member records of ~10,808,784 registered app users (~all): member number, registered name, email, phone. NOT leaked: login passwords, DOB, gender, postal code, points, store usage history. Payment cards not held by company. Other Monogatari brand apps: no leak confirmed.
Technical writeup
Verified company notice — Monogatari Corporation Oct 5, 2026: unauthorized access to Yakiniku King official app member management system. Access detected Oct 2; communications blocked/defenses applied; member-information leak confirmed Oct 3. 10,788,963 records out of 10,808,784 registrations affected (nearly all users). Leaked: member number, app-registered name, email, phone. Not leaked: passwords, DOB, gender, postal code, points, store history. Cards not retained. App continues after security measures; other brand apps not confirmed leaked. No confirmed public dump or misuse at notice. recordsAffected 10788963; companyConfirmed true.
Root cause
Unauthorized access to Yakiniku King official-app member management system detected Oct 2, 2026; member-data exfiltration confirmed Oct 3. Cause under investigation.