Act on Prohibition of Unauthorized Computer Access

The Act on the Protection of Personal Information (APPI) and its cybersecurity-adjacent provisions under the Unauthorized Computer Access Law (UCPA) form Japan's primary cybersecurity legal framework. The UCPA, enacted in 2000 and significantly amended in 2012, prohibits unauthorized access to computer systems and imposes criminal penalties. The law applies to any person who accesses a computer without authorization or exceeds their access rights. Japan's approach is notable for its emphasis on criminal deterrence rather than regulatory compliance frameworks, distinguishing it from EU and US models. The Ministry of Internal Affairs and Communications (MIC) and the National Police Agency (NPA) jointly oversee enforcement. Organizations operating in Japan must implement access control measures, maintain audit logs, and report significant cyber incidents to NISC (National center of Incident readiness and Strategy for Cybersecurity). The 2022 APPI amendments introduced mandatory breach notification within 72 hours for incidents affecting 1,000+ individuals, aligning Japan more closely with GDPR standards.