Kokuji

The term kokuji in Japanese can refer to any character created outside of China, including Korean gukja (國字, 국자) and Vietnamese chữ Nôm. Wasei kanji refers specifically to kanji invented in Japan.

Historically, some kokuji date back to very early Japanese writing, being found in the Man'yōshū, for example—鰯 iwashi "sardine" dates to the Nara period (8th century)—while they have continued to be created as late as the late 19th century, when a number of characters were coined in the Meiji era for new scientific concepts. For example, some characters were produced as regular compounds for some (but not all) SI units, such as 粁 (米 "meter" + 千 "thousand, kilo-") for kilometer, 竏 (立 "liter" + 千 "thousand, kilo-") for kiloliter, and 瓩 (瓦 "gram" + "thousand, kilo-") for kilogram. However, SI units in Japanese today are almost exclusively written using rōmaji or katakana such as キロメートル or ㌖ for km, キロリットル for kl, and キログラム or ㌕ for kg.^[2]

In Japan, the kokuji category is strictly defined as characters whose earliest appearance is in Japan.^[3] If a character appears earlier in the Chinese literature, it is not considered a kokuji even if the character was independently coined in Japan and unrelated to the Chinese character (meaning "not borrowed from Chinese"). In other words, kokuji are not simply characters that were made in Japan, but characters that were first made in Japan. An illustrative example is ankō (鮟鱇, monkfish). This spelling was created in Edo period Japan from the ateji (phonetic kanji spelling) 安康 for the existing word ankō by adding the 魚 radical to each character—the characters were "made in Japan". However, 鮟 is not considered kokuji, as it is found in ancient Chinese texts as a corruption of 鰋 (魚匽). 鱇 is considered kokuji, as it has not been found in any earlier Chinese text. Casual listings may be more inclusive, including characters such as 鮟.^{[note 1]} Another example is 搾, which is sometimes not considered kokuji due to its earlier presence as a corruption of Chinese 榨.

There are hundreds of kokuji in existence.^[4] Many are rarely used, but a number have become commonly used components of the written Japanese language. These include the following:

Jōyō kanji has about nine kokuji; there is some dispute over classification, but the following are generally included:

• 働 どう dō, はたら(く) hatara(ku) "work", the most commonly used kokuji, used in the fundamental verb hatara(ku) (働く, "work"), included in elementary texts and on the Proficiency Test N5.
• 込 こ(む) ko(mu), used in the fundamental verb komu (込む, "to be crowded")
• 匂 にお(う) nio(u), used in common verb niou (匂う, "to smell, to be fragrant")
• 畑 はたけ hatake "field of crops"
• 腺 せん sen, "gland"
• 峠 とうげ tōge "mountain pass"
• 枠 わく waku, "frame"
• 塀 へい hei, "wall"
• 搾 しぼ(る) shibo(ru), "to squeeze" (disputed; see above);

Jinmeiyō kanji:

• 榊 さかき sakaki "tree, genus Cleyera"
• 辻 つじ tsuji "crossroads, street"
• 匁 もんめ monme (unit of weight)

Hyōgaiji kanji:

• 躾 しつけ shitsuke "training, rearing (an animal, a child)"

Some of these characters (for example, 腺, "gland")^[5] have been introduced to China; additionally, Standard Mandarin readings are assigned to some kokuji used in Japanese toponymy, for example by the Guobiao standard GB/T 17693.10.^[6] In some cases, the Chinese reading is the inferred Chinese reading, interpreting the character as a phono-semantic compound (as in how on readings are sometimes assigned to these characters in Chinese), while, in other cases (such as 働), the Japanese on reading is borrowed (in general this differs from the modern Chinese pronunciation of this phonetic). Similar coinages occurred to a more limited extent in Korea and Vietnam.

• Gukja, Chinese characters created in Korea.
• Chữ Nôm, Chinese characters created in Vietnam.
• Sawndip, Chinese characters created by the Zhuang people.
• Wasei-kango, words in the Japanese language composed of Chinese morphemes but invented in Japan.
• Ryakuji, colloquial simplifications of kanji in Japan.