Jukujikun: Japanese Words You Can't Read From the Kanji
You learned that 今 is いま and 日 is にち — so why is 今日 read きょう? Because it is a jukujikun (熟字訓): a reading attached to the whole word, not to the individual kanji. You cannot derive these. You memorize them — and the good news is the common ones are a short list.
What Jukujikun Is
Most kanji compounds are read by combining the readings of each character (音読み or 訓読み). A jukujikun breaks that rule: the reading is assigned to the whole combination of kanji as a single unit.
So 大人 is not だい+じん — it is simply おとな. Trying to “sound it out” will only mislead you. Treat each jukujikun as one vocabulary item with its own reading.
Everyday Jukujikun to Memorize
How to Learn Them
- Learn them as whole words, never by adding up the kanji.
- They are high-frequency — 今日, 明日, 大人 appear constantly, so the effort pays back fast.
- Group by theme (time words, people, places) to make them stick.
Teacher's Note
Don't be frustrated that these “break the rules.” They are leftovers from how Japanese matched native words to Chinese characters. There are only a few dozen you truly need at N5–N3 — learn those and you have covered almost every jukujikun you'll meet daily.
Frequently Asked Questions
What is jukujikun (熟字訓)?
Jukujikun are compound words whose reading is assigned to the whole word, not built from the individual kanji readings. 今日 is read きょう (not いま+ひ), 大人 is おとな, 昨日 is きのう. You simply have to memorize the word as a unit.
Are jukujikun tested on the JLPT?
Yes — everyday jukujikun like 今日, 明日, 昨日, 大人, 上手, 下手, 時計, 一人 and 二人 appear from JLPT N5 onward in the kanji-reading section, precisely because their readings can't be guessed from the parts.
How is jukujikun different from onyomi and kunyomi?
Onyomi and kunyomi are readings attached to a single kanji. Jukujikun bypasses per-character readings entirely: the reading belongs to the whole compound. That's why knowing 大 (だい/おお) and 人 (じん/ひと) still won't give you おとな.
Memorize the readings that matter
Nihongo Pass drills high-frequency words — jukujikun included — with spaced repetition and native audio.
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