The Japanese national flag (Hi-no-Maru) is a good instance of Amiel's axiom that "nothing real is simple." The sun upon a background,-why should not the idea have been hit upon at once by the inhabitants of this "Land of the Rising Sun?" And yet, when we come to look into the matter, we find this apparently obvious result to have been evolved from a strangely complicated set of ideas, slowly changing through the centuries.
It seems that, from time immemorial, the Chinese Court and army had made use of banners adorned with figures founded on astrological fancies,-the Sun with the Three-legged Crow that inhabits it, the Moon with its Hare and Cassia-tree, the Red Bird representing the seven constellations of the southern quarter of the zodiac, the Dark Warrior (a Tortoise) embracing the seven northern constellations, the Azure Dragon embracing the seven eastern, the White Tiger embracing the seven western, and a seventh banner representing the Northern Bushel (Great Bear). The banners of the Sun and Moon assumed special importance, because the Sun was the Emperor's elder brother and the Moon his sister, for which reason he himself was, and still is, styled the Son of Heaven,-no mere metaphors these to the early Chinese mind, which implicitly believed that the Emperor's conduct could influence the course of the seasons.
The Japanese took over these things wholesale,-Imperial title, banners, mythological ideas, and all,-probably in the seventh century, for the official annals incidentally record their use in A.D. 700. In process of time most of the elements of this system were dropped, only the Sun and Moon Banners being retained as Imperial insignia, but without their fabulous inmates, though the Sun Crow and the Moon Hare still linger on in art. For such heathen fancies mediæval piety substituted effigies of the gods or an invocation to Buddha; but these, too, were dropped when Buddhist influence declined. Thus the sun (not originally a rising sun) alone remained; and when, in 1859, a national flag corresponding to those of Europe became necessary, the Sun Banner naturally stepped into the vacant place. A more elaborate design - the sixteen-petalled chrysanthemum, which is apparently only in another shape the sun with its rays- became fixed as the Imperial standard; for conformity to European usage prescribed such a distinction. The military flag with its sixteen rays is a modification of the same idea, the number sixteen itself being traceable to Chinese geomantic notions.
Book recommended - The above article is condensed from a beautifully illustrated paper by Mr. W. G. Aston, in Vol. XXII. of the Asiatic Transactions.