Japan's cybersecurity agency was reportedly breached by Chinese state hackers for 9 months before it was discovered.
Japan’s National Center of Incident Readiness and Strategy for Cybersecurity (NISC) announced in August that personal data linked to email exchanges may have been compromised after it was hacked in October last year.
It was also reported by the Washington Post that the US NSA found Chinese military hackers have also breached the Japanese Defense networks.