Since ancient times the Japanese had encountered the Kuroshio frequently. For instance some records about long-distance driftings along the south coast of Japan or across the East China Sea are found in Nihon Shoki (Official Record of Japan before 697), Shoku Nihongi (Official Record of Japan from 697 to 806) and Todai Wajo Tosei Den (Biography of Ganjin, an outstanding Chinese Buddhist). In the seventh and eights centuries, some ships of the Japanese envoy to China in the Tang Dynasty crossed the Kuroshio in the East China Sea, despite frequent incidents of ship wrecks. In the Momoyama and early Edo periods (1592-1635) the Shuinsen, Japanese ships with the Shogunate license for foreign trade, crossed the Kuroshio east of Taiwan bound for Luzon. Nevertheless, no mention of the Kuroshio was found in these periods. Since records of no mention of the Kuroshio in maritime literatures in old days will be helpful in this kind of study in the future, efforts are made to list a detailed bibliography. Finally, studies on terms "Rakusei" and "Biryo", the Chinese equivalents of "Kuroshio", are made on the basis of Chinese classics. The term "Rakusei" was cited in Japanese books in the Edo period, but the term "Biryo" was too legendary to be used in Japan as indicating the Kuroshio, although Needham et al. (1971) made extensively a historical study on "Biryo".

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The dinoflagellate Gymnodinium mikimotoi Miyake et Kominami ex ODA is responsible for prodigious red tides in western Japan. To clarify the mechanism by which the distribution of this organism expands and to examine associated environmental features, weekly observations were made at 37 stations in the Suo-Nada and the Iyo-Nada, in the western Seto Inland Sea, during May through August from 1989 to 1991. The initial appearance of G. mikimotoi was observed in the southwestern region of the Suo-Nada. This region was characterized by high water temperature and low salinity in comparison with the surrounding areas. In 1991, high cell densities of G. mikimotoi were observed in this region following the occurrence of low oxygen concentrations in the bottom layer in July. This increased growth of G. mikimotoi may have been due to the increase in dissolved inorganic nitrogen concentrations which accompanied the decrease in oxygen concentrations. The motile cells of G. mikimotoi in the southwestern region of Suo-Nada were introduced to other areas through diffusion of the upper water mass as a consequence of the breakdown of the stratification in this region, resulting in the expansion of the distribution of G. mikimotoi in the western Seto Inland Sea. It was also determined that the northern coast of the Suo-Nada is also a possible area for the initial appearance of this species. The cells that first appear in the Iyo-Nada may originate from the Suo-Nada, the eastern coast of Yamaguchi prefecture, and/or the southwestern area of Hiroshima Bay.

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