Overview
Per-system counts (HR/payroll 6,167; health 31,766; child consultation 2,185) are not summed (count blank). Includes My Number and health-check fields.
Timeline
- Occurred
- Discovered
- Disclosed
Organization response
Per the notice, the organisation investigated and contained the incident, notified individuals and offered monitoring or protective resources.
What you can do
Be wary of emails, SMS or calls impersonating the organisation; do not open links or attachments or enter passwords or card details. Change reused passwords on other services.
Sources
- 株式会社YCC情報システムに対するサイバー攻撃に係る山形市保有個人情報の漏えいのおそれがある事案について山形市 · 2026-11-09