A massive data breach at Aflac Japan has compromised the personal data of 4.38 million individuals, following a series of unauthorized accesses to the company's policyholder portal between June 15 and June 25. The incident highlights the vulnerability of insurance companies' online platforms to cyber threats. The breach is particularly concerning given the sensitive nature of the data stored on such platforms, which can include policyholders' personal and financial information. The frequency of the unauthorized accesses over a 10-day period raises questions about the effectiveness of Aflac Japan's security measures1. The company's response to the breach will be closely watched, as regulators and customers alike demand greater accountability from organizations that handle sensitive data. This breach matters to cybersecurity practitioners because it underscores the need for robust access controls and monitoring to prevent and detect such incidents, which can have severe consequences for both individuals and organizations.