Modern kana usage

General differences

There were no small kana in the pre-reform system; thus, for example, きよ would be ambiguous between kiyo and kyo while かつた could be either katsuta or katta.

The pronunciation of medial h-row kana as w-row kana in the pre-reform system does not extend to compound words; thus, にほん was pronounced nihon, not nion (via **niwon). There are a small number of counterexamples; e.g., あひる "duck", pronounced ahiru rather than airu, or ふぢはら, pronounced Fujiwara, despite being a compound of Fuji (wisteria) + hara (field). The h-row was historically pronounced as fa, fi, fu, fe, fo (and even further back, pa, pi, pu, pe, po). Japanese f (IPA: ) is close to a voiceless w, and so was easily changed to w in the middle of a word; the w was then dropped except for わ wa. This is also why fu is used to this day and has not become hu.

The vowel + (f)u changes do not apply between elements of compound words, for example, the name てらうち was Terauchi not Terōchi, as it is Tera (temple) + uchi (inside, home). The -fu of the modern -u series of verbs (that is, those verbs using the actual kana う, such as kau or omou) was not affected by the sound changes on the surface; however, some reports of Edo era Japanese indicate that verbs like tamau and harau were pronounced as tamō and harō instead. In contrast, the -ō in darō and ikō is a product of the sound change from au to ō.

Furthermore, the topic particle wa (は), the direction particle e (へ) and the direct object particle o (を) were exempted from spelling reform. In contemporary Japanese, the を-character is used only for the particle. Some innovative writers before the official reform went so far as to write the topic particle wa as わ. For example, the educator Ishikawa Kuraji wrote his innovatively space-separated and softly hyphenated hiragana text with わ instead of は and え instead of へ, although he still kept を.

Examples

Here, for example, あ (a) includes all kana using the /a/ vowel, such as か (ka) or た (ta).

Regarding じぢずづ – these four morae are distinguished or merged to varying degrees in different Japanese dialects, with some dialects (Tōhoku and Okinawan, for example) merging all four into one, while other dialects (Tosa and Satsugū, for example) distinguish among the four. Standard spelling reflects the pronunciation of standard Japanese, which merges these into two sounds.