Kokutai is a Japanese term. It may refer to: Kokutai, a Japanese word used during the second half of the 19th century and first half of the 20th century to refer to the emperor sovereignty Kokutai, a Japanese abbreviation for the Kokutai-ji, Kōkūtai (Naval Air Group), a type of aerial combat unit used by the Imperial Japanese Navy Air Service during World War II. Current Japan Air Self Defense Force.