Kurogane Kasei: ransomware attack may expose names and contacts of partners, staff and applicants

1. 2025-10-16

   A system failure, apparently caused by unauthorized access to some servers, occurred; the company began investigating with outside experts. Production was not affected. [1] [2]

2. 2025-10-24

   Kurogane Kasei and its parent KH Neochem disclosed the attack. [1] [2]

3. 2025-10-31

   The second report said the attack was ransomware and that entry was most likely through a VPN device. [3]

4. 2026-10-28

   Based on the investigation, the company disclosed that personal data had leaked or may have leaked. [4]

Business partners, officers and employees (including former ones) and job applicants are affected: names, addresses, phone numbers, email addresses, job titles, departments and more. My Number data is not included, and no count has been published. No secondary damage has been reported. [4]

The company is notifying affected people individually, reporting to the authorities, and carrying out recovery and preventive measures. [4]