Provincial differences of copula daDozens of dialects are spoken in Japan. The profusion is due to many factors, including the length of time the archipelago has been inhabited, its mountainous island terrain, and Japan's long history of both external and internal isolation. Dialects typically differ in terms of pitch accent, inflectional morphology, vocabulary, and particle usage. Some even differ in vowel and consonant inventories, although this is uncommon.
The main distinction in Japanese accents is between Tokyo-type (東京式 ,Tōkyō-shiki?) and Kyoto-Osaka-type (京阪式 ,Keihan-shiki?), though Kyūshū-type dialects form a third, smaller group. Within each type are several subdivisions. Kyoto-Osaka-type dialects are in the central region, with borders roughly formed by Toyama, Kyōto, Hyōgo, and Mie Prefectures; most Shikoku dialects are also that type. The final category of dialects are those that are descended from the Eastern dialect of Old Japanese; these dialects are spoken in Hachijō-jima island and few islands.
Dialects from peripheral regions, such as Tōhoku or Tsushima, may be unintelligible to speakers from other parts of the country. The several dialects of Kagoshima in southern Kyūshū are famous for being unintelligible not only to speakers of standard Japanese but to speakers of nearby dialects elsewhere in Kyūshū as well. This is probably due in part to the Kagoshima dialects' peculiarities of pronunciation, which include the existence of closed syllables (i.e., syllables that end in a consonant, such as /kob/ or /koʔ/ for Standard Japanese /kumo/ "spider"). A dialects group of Kansai is spoken and known by many Japanese, and Osaka dialect in particular is associated with comedy (See Kansai dialect). Dialects of Tōhoku and North Kantō are associated with typical farmers.
The Ryūkyūan languages, spoken in Okinawa and Amami Islands that are politically part of Kagoshima, are distinct enough to be considered a separate branch of the Japonic family. But many Japanese common people tend to consider the Ryūkyūan languages as dialects of Japanese. Not only is each language unintelligible to Japanese speakers, but most are unintelligible to those who speak other Ryūkyūan languages.
Recently, Standard Japanese has become prevalent nationwide (including the Ryūkyū islands) due to education, mass media, and increase of mobility networks within Japan, as well as economic integration.
source : wikipedia