Hyōgaiji (表外字, translated to "characters from outside the table/chart"), also hyōgai kanji (表外漢字) and jōyōgai kanji (常用外漢字), are Japanese kanji outside the two major lists of Jōyō, which are taught in primary and secondary school, and Jinmeiyō, which are additional kanji that officially are allowed for use in personal names.
Because hyōgaiji is a catch-all category for "all unlisted kanji", there is no comprehensive list, nor is there a definitive count of the hyōgaiji. The highest level of the Kanji kentei (test of kanji aptitude) tests approximately 6,000 characters, of which 3,000 are hyōgaiji, while in principle any traditional Chinese character or newly coined variant may be used as hyōgaiji; the traditional dictionaries the Kangxi Dictionary and the 20th century Dai Kan-Wa jiten contain about 47,000 and 50,000 characters, respectively, of which over 40,000 would be classed as hyōgaiji or non-standard variants if used in Japanese.
While many jōyō-kanji are printed using simplified forms (shinjitai, in opposition to traditional forms), hyōgaiji are officially printed with traditional forms such as 臍, even if some simplified variants are officially recognized in print, such as 唖.
Jinmeiyō-kanji list (used for names) recognizes in most cases traditional form and simplified form — when it exists.
However, other unofficial simplified forms exist, known as extended shinjitai (拡張新字体, kakuchō shinjitai) – these come by applying the same simplification processes as in the development of shinjitai. The newspaper Asahi Shimbun developed its own simplified characters, known as Asahi characters, and they have their own Unicode code points. Some of these simplifications are part of the standard JIS X 0208 and later versions. Among extended shinjitai, only a few are de facto frequently used, including 填, 頬 (extended shinjitai for the jōyō-kanji 塡, 頰) or 涜, 掴 (extended shinjitai for the hyōgaiji 瀆, 摑).
The issue of variant non-Jōyō character forms becomes apparent when using many commonly available Japanese fonts. While characters not frequently used generally retain their traditional forms, those commonly used in Japanese writing frequently are reproduced in their unofficial simplified form (extended shinjitai), rather than their official printed form. Well-known examples include:麺 (MEN, "noodles"; with simplified radical, instead of official 麵),
掴 (KAKU, tsuka(mu), "catch"; with simplified onpu, rather than official 摑), and
鴎 (Ō, kamome, "seagull"; with simplified onpu, rather than official 鷗).
Some characters are provided in both their official and simplified forms, as is the case with 攪 (official printed form) and 撹 (simplified variant), but most of these characters are provided in one form only. Thus, unlike the aforementioned "Asahi characters", simplifications are not comprehensive, meaning that hyōgaiji are rendered as a mix of both standard classical forms and unofficial simplifications. This is perhaps most obvious in the archaic kanji spelling of pan ("bread"), 麺麭. The characters, both hyōgaiji, are displayed with a simplified and an unsimplified "barley" radical side-by-side, which can be visually jarring. The lack of an unsimplified variant in many fonts leaves the user with no choice but to reproduce the word as shown above.
The use of hyōgaiji in computer fonts was brought to the fore with the 2007 launch of Mac OS X v10.5 "Leopard". This release included the fonts Hiragino Mincho Pro N and Hiragino Kaku Gothic Pro N, which reproduce hyōgaiji in their official printed forms.
A related weakness (though less relevant to modern language use) is the inability of most commercially available Japanese fonts to show the traditional forms of many Jōyō kanji, particularly those whose component radicals have been comprehensively altered (such as 食 in 飲, 示 in 神, and 辵 in 運 or 連, rather than their traditional forms as used in 饅, 祀, and 迴). This is mostly an issue in the verbatim reproduction of old texts, and for academic purposes.
Hyōgaiji are often used in the names of wagashi, which draw from ancient literature.
Hyōgai kanji may be often used in manga works for stylistic purposes in character names, place names and other phrases, typically accompanied by furigana gloss to aid with their reading.
Modern Mandarin Chinese borrowings into Japanese are typically rendered with katakana as per any gairaigo, however they may be sometimes stylistically spelled with their original Chinese characters and given a non-standard borrowed pronunciation, many of these characters are technically classified as Hyōgaiji due to the difference in common character use between the languages.