Early Middle Japanese

The is a stage of the Japanese language between 794 and 1185, which is known as the Heian Period. The successor to Old Japanese, it is also known as the Late Old Japanese. However, the term "Early Middle Japanese" is preferred, as it is closer to Late Middle Japanese (after 1185) than to Old Japanese (before 794).
Background.
Old Japanese had borrowed and adapted the Chinese script to write Japanese. In Early Middle Japanese, two new scripts emerged: the kana scripts hiragana and katakana. That development simplified writing and brought about a new age in literature with many classics such as "The Tale of Genji", "The Tale of the Bamboo Cutter", and "The Tales of Ise".
Phonology.
Developments.
Major phonological changes were characteristic of the period.
The most prominent difference was the loss of the Jōdai Tokushu Kanazukai, which distinguished two types of /i/, /e/ and /o/. While the start of the loss can already be seen at the end of Old Japanese, it was completely lost in Early Middle Japanese. The final distinction to be lost was /ko1, go1/ vs. /ko2, go2/.
In the 10th century, /e/ and /je/ merged into /je/, and /o/ and /wo/ had merged into /wo/ by the 11th century.
An increase in Chinese loanwords had a number of phonological effects:
The development of the uvular nasal and geminated consonants occurred late in the Heian period and brought about the introduction of closed syllables (CVC).
Phonetics.
Phonetic Realization.
Theories for the realization of include , , and . It may have varied depending on the following vowel, like in Modern Japanese. 
By the 11th century, had merged with between vowels.
Grammar.
Syntactically, Early Middle Japanese was an subject-object-verb language with a topic-comment structure. Morphologically, it was an agglutinative language. Major word classes were nouns and pronouns, verbs, adjectives, adverbs, and various grammatical particles. Nouns could be followed by particles to indicate case but also occurred without particle. Verbs had to be marked with affixes, many of which were inflected as verbs in their own right and so allowed the accumulation of complex strings of suffixes. Adjectives were largely inflected for the same categories as verbs and so are often referred to as stative verbs.
Nouns and pronouns.
Nouns occurred with postpositive case particles such as these:
The nominative function was marked by the absence of a particle in main clauses and by the genitive particles in subordinate clauses. The dative/locative particle "-ni" was homophonous with the simple infinitive form of the copula "-ni", with verbal suffixes supplies more complex case markers "-ni-te" ('at' a place) and "-ni si-te" or "-ni-te" ('by means of'). A number of particle + verb + "-te" sequences provided other case functions: "-ni yori-te" 'due to' (from "yor"- 'depend'), -"ni tuki-te" 'about, concerning' (from "tuk"- 'be attached'), and -"to si-te" 'as' (from "se-" 'do'). More complex structures were derived from genitive particle + Location Noun + appropriate case particle (typically locative "-ni") and were used particularly to express spatial and temporal relations. Major location nouns were "mafe" 'front' (Noun-"no mafe-ni" 'in front of Noun'), "ufe" 'top' (Noun-"no ufe-ni" 'on top of Noun' ~ 'above Noun'), "sita" 'under' (Noun-"no sita-ni" 'under Noun), "saki" 'ahead' (Noun-"no saki-ni" 'ahead of Noun)', etc.
Verbs.
Early Middle Japanese verb inflection was agglutinative. All verbs were conjugated in a small number of 'stems' and could be combined with grammaticalized verbs to express tense, aspect, mood, voice, and polarity. Several of the grammaticalized verbs could combine in a string, and each component determined the choice of stem of the preceding component. A small number of other grammatical endings were not verbs but carried various co-ordinating or subordinating functions.
Early Middle Japanese inherited all eight verbal conjugations from Old Japanese and added one new one: Lower Monograde.
Conjugation.
Traditionally, verbs were divided into five regular conjugations: quadrigrade ("yodan" 四段), upper monograde ("kami ichidan" 上一段), lower monograde ("shimo ichidan" 下一段), upper bigrade ("kami nidan" 上二段), lower bigrade ("shimo nidan" 下二段). There were also four 'irregular' conjugations: K-irregular ("kahen" カ変), S-irregular ("sahen" サ変), N-irregular ("nahen" ナ変), R-irregular ("rahen" ラ変). The conjugation of each is divided into six stems: irrealis ("mizenkei" 未然形), infinitive ("ren'yōkei" 連用形), conclusive ("shūshikei" 終止形), attributive ("rentaikei" 連体形), realis ("izenkei" 已然形), and imperative ("meireikei" 命令形). The English names for the irrealis and the realis differ from author to author, including negative and evidential, imperfective and perfective, or irrealis and realis.
The system of nine conjugation classes appears to be complex. However, all nine conjugations can be subsumed into variations of two groups: the consonant-root verbs, and the vowel-root verbs. Consonant-root verbs were quadrigrade, N-irregular and R-irregular verbs. The irregularity of N-irregular verbs occurred only in the conclusive and the attributive, and as there are no quadrigrade verbs with "n"-roots, quadrigrade and N-irregular verb patterns may be treated as being in complementary distribution. Vowel-root verbs consist of bigrade verbs (the majority), a few monograde verbs (especially "mi"- 'see' and "wi"- 'sit'), the K-irregular verb "ko"- 'come', and the S-irregular verb "se"- 'do' (or -"ze"- in some compounds). The difference between 'upper' and 'lower' bigrade or monograde verbs is whether the vowel at the end of the root was "i" or "e". There was only one 'lower' monograde verb, "kwe"- 'kick', which was a 'lower' bigrade verb "kuwe"- in Old Japanese, changed pronunciation to "ke"- in early Late Middle Japanese (completed around 1300), and changed conjugation class again in later Japanese to become quadrigrade (Modern Japanese "ker"-). The difference between bigrade and monograde was whether in the conclusive, attributive and realis the initial "u" of the ending elided the vowel of the root or the vowel of the roots elides the initial "u" of the ending.
There are problems with that arrangement of stems.
Verb endings.
Verb endings are attached agglutinatively to the various stems of verbs. They are divided into endings that behave like verbs themselves and endings that act as conjunctions.
Verb-like endings.
Verb-like endings behaved like verbs in that they exhibited all or most of the stems that a lexical verb exhibits. The usual forms are listed below, and the way in which they were attached to the preceding verb follows the revised system of stems above. A verb could be followed by several such endings in a string.
Voice: 'passive' and 'causative':
Tense/Aspect:
Other aspectual functions can be expressed with auxiliaries that also exist as independent verbs:
Other auxiliaries express direction, either literally or metaphorically.
Mood:
Polarity:
Adjectives.
There were two types of adjectives: regular adjectives and adjectival nouns.
The regular adjective was subdivided into two types: those for which the adverbial form ended in -"ku" and those that ended in -"siku". That created two different types of conjugations:
The class of siku-adjectives included a few adjectives that had "z", rather than "s": adverbial -"ziku", conclusive -"zi", attributive -"ziki"., e.g. "imizi" 'be terrible'. "Onazi" 'be the same' usually had -"zi" rather than -"ziki", in its attributive form.
The -"kar"- and -"sikar"- forms were derived from the verb "ar"- "be, exists." The adverbial conjugation (-"ku" or -"siku") was suffixed with ar-. The conjugation yielded to the r-irregular conjugation of "ar"-. The resulting -"ua"- elided into -"a"-.
The adjectival noun kept the original "nar"- conjugation and added a new "tar"-:
The "nar"- and "tar"- forms shared a common etymology. The "nar"- form was a contraction of the case particle "ni" and the r-irregular verb "ar"- "is, be": "ni" + "ar"- > "nar"-. The "tar"- form was a contraction of the case particle "to" and the r-irregular verb "ar"- "is, be": "to" + "ar"- > "tar"-. Both derived their conjugations from the verb "ar"-.
Writing system.
Early Middle Japanese was written in three different ways. It was first recorded in Man'yōgana, which is Chinese characters that were used as a phonetic transcription. That later produced the hiragana and the katakana syllabic scripts, which were derived from simplifications of the original Chinese characters.