NCO

The National Cyber Office (NCO) is Japan's central cybersecurity coordination body, sitting under the Cabinet Secretariat of the Prime Minister's Office in Tokyo. The NCO is the successor to the National center of Incident Readiness and Strategy for Cybersecurity (NISC), which was established in 2015 under the Cybersecurity Basic Act; the nisc.go.jp domain now redirects to cyber.go.jp, confirming the organisational succession. The NCO coordinates cybersecurity policy across Japanese ministries, manages critical-infrastructure protection frameworks, and serves as Japan's interface with allied cyber agencies. It is not a signals intelligence or law enforcement body — those roles belong to the Cabinet Intelligence and Research Office (CIRO) and the National Police Agency (NPA) respectively. Japan's offensive and foreign SIGINT capacity resides primarily in the Japan Self-Defense Force's Cyber Defence Command.

Japan's NCO/NISC has faced scrutiny domestically following confirmed breaches of Japanese government systems by Chinese state-sponsored actors in 2023 and by other state actors in subsequent years, which prompted the organisational transition from NISC to the more senior NCO architecture.

The NCO (identified in the briefing as Japan's signatory, formerly under its NISC designation) was one of the sixteen national cyber agencies that signed the joint advisory on China-nexus covert networks on 23 April 2026. Japan's inclusion is particularly significant given its proximity to Chinese state cyber operations in the Pacific theatre and the known compromise of Japanese government networks in 2023. The advisory's formal acceptance that IOC-based defence is inadequate is consistent with the NCO's post-NISC reform trajectory, which has emphasised active cyber defence over reactive indicator sharing. Japan named in the advisory's scope includes energy and digital infrastructure operators across the Tokyo and Osaka metro corridors.