Japanese dialects

The dialects of the Japanese language fall into two primary clades, Eastern and Western, with the dialects of Kyushu and Hachijō Island often distinguished as additional branches, the latter perhaps the most divergent of all. The Ryukyuan languages of Okinawa Prefecture and the southern islands of Kagoshima Prefecture form a separate branch of the Japonic family, and are not Japanese dialects, although they are often referred to as such.
Japan with its numerous islands and mountains has the ideal setting for developing many dialects.

History

Regional variants of Japanese have been confirmed since the Old Japanese era. The Man'yōshū, the oldest existing collection of Japanese poetry, includes poems written in dialects of the capital and eastern Japan, but other dialects were not recorded. The compiler included azuma uta that show that eastern dialect traits were distinct from the western dialect of Nara. It is not clear if the capital of Nara entertained the idea of a standard dialect, however, they had an understanding which dialect should be regarded as the standard one, the dialect of the capital.
The recorded features of eastern dialects were rarely inherited by modern dialects, except for a few language islands such as Hachijo Island. In the Early Middle Japanese era, there were only vague records such as "rural dialects are crude". However, since the Late Middle Japanese era, features of regional dialects had been recorded in some books, for example Arte da Lingoa de Iapam, and the recorded features were fairly similar to modern dialects. In these works, recorded by the Christian missionaries in Japan, they regard the true colloquial Japanese as the one used by the court nobles in Kyōto. Other indications for the Kyōto dialect to be considered the standard dialect at that time are glossaries of local dialects that list the Kyōto equivalent for local expressions.
The variety of Japanese dialects developed markedly during the Early Modern Japanese era because many feudal lords restricted the movement of people to and from other fiefs. Some isoglosses agree with old borders of han, especially in Tohoku and Kyushu. Nevertheless, even with the political capital being moved to Edo the status of the Kyōto dialect was not threatened immediately as it was still the cultural and economic center that dominated Japan. This dominance waned as Edo began to assert more political and economic force and made investments in its cultural development. At the end of the eighteenth century the Japanese that was spoken in Edo was regarded as standard as all glossaries from this period use the Edo dialect for local expressions.
In the Meiji period the Tōkyō dialect was assuming the role of a standard dialect that was used between different regions to communicate with each other. The Meiji government set policies in place to spread the concept of 標準語. One of the main goals was to be an equal to the western world and the unification of the language was a part to achieve this. For the hyōjun-go the speech of the Tōkyō middle class served as a model. The Ministry of Education at this time made text books in the new standard language and fostered an inferiority complex in the minds of those who spoke in dialects besides the Tōkyō dialect. One example is a student who was forced to wear a "dialect tag" around the neck.
From the 1940s to the 1960s, the period of Shōwa nationalism and the post-war economic miracle, the push for the replacement of regional varieties with Standard Japanese reached its peak.
After World War II, the concept of 共通語 was introduced, which differed from the concept of the standard language insofar that it is heavily influenced by the standard language but it retains dialectal traits. Across Japan, the 'common language' productively used in everyday speech can differ from region to region but it is still mutually intelligible.
Now Standard Japanese has spread throughout the nation, and traditional regional varieties are declining because of education, television, expansion of traffic, urban concentration, etc, in a process known as dialect levelling. However, regional varieties have not been completely replaced with Standard Japanese. The spread of Standard Japanese means the regional varieties are now valued as "nostalgic", "heart-warming" and markers of "precious local identity", and many speakers of regional dialects have gradually overcome their sense of inferiority regarding their natural way of speaking. The contact between regional varieties and Standard Japanese creates new regional speech forms among young people, such as Okinawan Japanese.

Mutual intelligibility

In terms of mutual intelligibility, a survey in 1967 found the four most unintelligible dialects to students from Greater Tokyo are the Kiso dialect, the Himi dialect, the Kagoshima dialect and the Maniwa dialect. The survey is based on recordings of 12- to 20- second long, of 135 to 244 phonemes, which 42 students listened and translated word-by-word. The listeners were all Keio University students who grew up in the Kanto region.

Dialect	Osaka City	Kyoto City	Tatsuta, Aichi	Kiso, Nagano	Himi, Toyama	Maniwa, Okayama	Ōgata, Kōchi	Kanagi, Shimane	Kumamoto City	Kagoshima City
Percentage	26.4%	67.1%	44.5%	13.3%	4.1%	24.7%	45.5%	24.8%	38.6%	17.6%

Classification

There are several generally similar approaches to classifying Japanese dialects. Misao Tōjō classified mainland Japanese dialects into three groups: Eastern, Western and Kyūshū dialects. Mitsuo Okumura classified Kyushu dialects as a subclass of Western Japanese. These theories are mainly based on grammatical differences between east and west, but Haruhiko Kindaichi classified mainland Japanese into concentric circular three groups: inside, middle and outside based on systems of accent, phoneme and conjugation.

Eastern and Western Japanese

A primary distinction exists between Eastern and Western Japanese. This is a long-standing divide that occurs in both language and culture. Tokugawa points out the distinct eating habits, shapes of tools and utensils. One example is the kind of fish eaten in both areas. While the Eastern region eats more salmon, the West consumes more seabream.
The map in the box at the top of this page divides the two along phonological lines. West of the dividing line, the more complex Kansai-type pitch accent is found; east of the line, the simpler Tokyo-type accent is found, though Tokyo-type accents also occur further west, on the other side of Kansai. However, this isogloss largely corresponds to several grammatical distinctions as well: West of the pitch-accent isogloss:

The perfective form of -u verbs such as harau 'to pay' is harōta, showing u-onbin, rather than Eastern haratta
* The perfective form of -su verbs such as otosu 'to drop' is also otoita in Western Japanese vs. otoshita in Eastern
The imperative of -ru verbs such as miru 'to look' is miyo or mii rather than Eastern miro
The adverbial form of -i adjectival verbs such as hiroi 'wide' is hirō, showing u-onbin, for example hirōnaru, rather than Eastern hiroku, for example hirokunaru
The negative form of verbs is -nu or -n rather than -nai or -nee, and uses a different verb stem; thus suru 'to do' is senu or sen rather than shinai or shinee
The copula is da in Eastern and ja or ya in Western Japanese, though Sado as well as some dialects further west such as San'in use da
The verb iru 'to exist' in Eastern and oru in Western, though the Wakayama dialect also uses aru and some Kansai and Fukui subdialects use both

While these grammatical isoglosses are close to the pitch-accent line given in the map, they do not follow it exactly. Apart from Sado Island, which has Eastern shinai and da, all of the Western features are found west of the pitch-accent line, though a few Eastern features may crop up again further west. East of the line, however, there is a zone of intermediate dialects which have a mixture of Eastern and Western features. Echigo dialect has harōta, though not miyo, and about half of it has hirōnaru as well. In Gifu, all Western features are found apart from pitch accent and harōta; Aichi has miyo and sen, and in the west hirōnaru as well: These features are substantial enough that Toshio Tsuzuku classifies Gifu–Aichi dialect as Western Japanese. Western Shizuoka has miyo as its single Western Japanese feature.
The Western Japanese Kansai dialect was the prestige dialect when Kyoto was the capital, and Western forms are found in literary language as well as in honorific expressions of modern Tokyo dialect, such as adverbial ohayō gozaimasu, the humble existential verb oru, and the polite negative -masen, which uses the Kyoto-style negative ending -n. Because the imperial court, which put emphasis on correct polite speech, was located in Kyoto for a long time, there was greater development of honorific speech forms in Kyoto, which were borrowed into Tokyo speech. Another feature that the modern Tokyo dialect shares with Kyoto is the preservation of the vowel sequences,, and : in Eastern dialects, these tend to undergo coalescence and be replaced by, and respectively. Examples of words that originated in Kyoto and were adopted by Tokyo are yaru, kaminari and asatte.

Kyushu Japanese

Kyushu dialects are classified into three groups, Hichiku dialect, Hōnichi dialect and Satsugu dialect, and have several distinctive features:

as noted above, Eastern-style imperatives miro ~ mire rather than Western Japanese miyo
ka-adjectives in Hichiku and Satsugu rather than Western and Eastern i-adjectives, as in samuka for samui 'cold', kuyaka for minikui 'ugly' and nukka for atsui 'warm'
the nominalization and question particle to except for Kitakyushu and Oita, versus Western and Eastern no, as in tottō to? for totte iru no? 'is this taken?' and iku to tai or ikuttai for iku no yo 'I'll go'
the directional particle sai, though Eastern Tohoku dialect use a similar particle sa
the emphatic sentence-final particles tai and bai in Hichiku and Satsugu
a concessive particle batten for dakedo 'but, however' in Hichiku and Satsugu, though Eastern Tohoku Aomori dialect has a similar particle batte
is pronounced and palatalizes s, z, t, d, as in mite and sode, though this is a conservative pronunciation found with s, z in scattered areas throughout Japan like the Umpaku dialect.
as some subdialects in Shikoku and Chugoku, but generally not elsewhere, the accusative particle o resyllabifies a noun: honno or honnu for hon-o 'book', kakyū for kaki-o 'persimmon'.
is often dropped, for koi 'this' versus Western and Eastern Japanese kore
vowel reduction is frequent especially in Satsugu and Gotō Islands, as in in for inu 'dog' and kuQ for kubi 'neck'
Kyushu dialects share some lexical items with Ryukyuan languages, some of which appear to be innovations. Some scholars have proposed that Kyushu dialects and Ryukyuan languages are the same language group within the Japonic family.

Much of Kyushu either lacks pitch accent or has its own, distinctive accent. Kagoshima dialect is so distinctive that some have classified it as a fourth branch of Japanese, alongside Eastern, Western, and the rest of Kyushu.