Please add the language code ja-Hira, ja-Kana, ja-Hrkt, ja-Hani, ojp, ojp-Hira, ojp-Hani to the list of language codes supported for monolingual text values.
# ja-Hira
* Language code: ja-Hira
* Language name: Japanese Language written in hiragana
* Used script: hiragana (http://www.wikidata.org/entity/Q48332)
* Wikidata item: http://www.wikidata.org/entity/Q53979341
* Usage example: ① Lemme of http://www.wikidata.org/entity/L545 (Japanese verb, "eat") → "食べる"＠ja and "たべる"＠ja-Hira, ② Word stem (http://www.wikidata.org/entity/P5187) of L545 → "食"＠ja and "た"＠ja-Hira
# ja-Kana
* Language code: ja-Kana
* Language name: Japanese Language written in katakana
* Used script: hiragana (http://www.wikidata.org/entity/Q82946)
* Wikidata item: http://www.wikidata.org/entity/Q53979342
* Usage example: Lemme of http://www.wikidata.org/entity/L375 (Japanese noun, "cat") → "猫"＠ja and "ネコ"＠ja-Kana (and "ねこ"＠ja-Hira)
# ja-Hrkt
* Language code: ja-Hrkt
* Language name: Japanese Language written in kana (hiragana + katakana)
* Used script: kana (http://www.wikidata.org/entity/Q187659)
* Wikidata item: http://www.wikidata.org/entity/Q53979345
* Usage example: Lemme of http://www.wikidata.org/entity/L1894 (Japanese noun, "Orion") → "オリオン座"＠ja and "オリオンざ"＠ja-Hrkt
# ja-Hani
* Language code: ja-Hani
* Language name: Japanese Language written in kanji
* Used script: kanji (http://www.wikidata.org/entity/Q82772)
* Wikidata item: http://www.wikidata.org/entity/Q53979504
* Usage example: ①Lemme of http://www.wikidata.org/entity/L1898 (Japanese noun, "lemon") → "レモン"＠ja (ja-Kana) and "檸檬"＠ja-Hani ②Lemme of http://www.wikidata.org/entity/L1899 (Japanese noun, "swing seat") → "ブランコ"＠ja (ja-Kana), "ぶらんこ"＠ja-Hira and "鞦韆"＠ja-Hani
# ojp
* Language code: ojp
* Language name: (Late) Old Japanese Language
* Used script: kanji + kana
* Wikidata item: http://www.wikidata.org/entity/Q182695
* Usage example: ①Old Japanese adjective for "beautiful" (lexeme not created yet) → "美し"＠ojp and "うつくし"＠ojp-Hira, ② Word stem (http://www.wikidata.org/entity/P5187) of ① → "美"＠ojp and "うつく"＠ja-Hira
# ojp-Hira
* Language code: ojp-Hira
* Language name: (Late) Old Japanese Language written in hiragana
* Used script: hiragana (http://www.wikidata.org/entity/Q48332)
* Wikidata item: http://www.wikidata.org/entity/Q54086472
* Usage example: ①Old Japanese adjective for "beautiful" (lexeme not created yet) → "美し"＠ojp and "うつくし"＠ojp-Hira, ② Word stem (http://www.wikidata.org/entity/P5187) of ① → "美"＠ojp and "うつく"＠ja-Hira
# ojp-Hani
* Language code: ojp-Hira
* Language name: (Late) Old Japanese Language written in hiragana
* Used script: kanji (http://www.wikidata.org/entity/Q82772)
* Wikidata item: http://www.wikidata.org/entity/Q54086473
* Usage example: Old Japanese adverb for "almost" (lexeme not created yet) → "おほよそ"＠ojp (ojp-Hira) and "大凡"＠ojp-Hani
**Reason:**
The Japanese language is written in the combination of kanji (Chinese characters), hiragana and katakana scripts, so its words have many notation variabilities (kanji[+hiragana] vs hiragana, hiragana vs katakana, katakana vs kanji, etc) in the standard Japanese. In association with the release of lexicographical data support on Wikidata, we need to distinguish the Japanese texts by their written scripts. For example, currently the lexeme http://www.wikidata.org/entity/L545 has only one lemme "食べる"＠ja, but "たべる"＠ja (ja-Hira) should also be the lemme of this lexeme. Word stem (http://www.wikidata.org/entity/P5187) of L545 can take both "食"＠ja and "た"＠ja (ja-Hira), too.
Also, like the language code "ang" (Old English), "ojp" is needed to represent the Old Japanese words, whose grammar is very different to that of the current Japanese language. And "ojp-Hira" and "ojp-Hani" are required for the same reason.