National Foundation Day (建国記念の日, Kenkoku Kinen no Hi) is an annual national holiday in Japan on February 11, celebrating the foundation of Japan, enforced by a specific Cabinet Order set in 1966.National Foundation Day (建国記念の日, Kenkoku Kinen no Hi) is an annual national holiday in Japan on February 11, celebrating the foundation of Japan, enforced by a specific Cabinet Order set in 1966.