八紘 (hakkō, “eight corners”) + 一宇 (ichiu, “one roof”) ≅ “the eight corners of the earth [united] under a single roof”
The concept originates from a passage in the Nihon Shoki (720): 兼六合以開都、 掩八紘一而為宇, in which Emperor Jimmu declares Kashihara to be the capital of the lands. Originally limited to context of Japan as a whole, but in 1903 Tanaka Chigaku first used it in reference to world unification. Widely used around 1937 during the Sino-Japanese War, the phrase was later included in the July 26, 1940 national policy known as Kihon Kokusaku Yōkō (基本国策要綱) during the Fumimaro Konoe administration.
八紘一宇(hiragana はっこういちう, romaji hakkō ichiu)
- unifying and controlling the whole of world as a single house
- during World War II, used as a nationalistic slogan to rationalize oversea expansion