What the tail is doing
A Japanese verb has a stem that does not change and an ending that does. The kanji carries the stem and the kana carries the ending, which is why the kana changes as the verb conjugates while the kanji stays put.
That division is the whole idea. Once you see it, conjugation becomes visually obvious on the page: the part that moves is written in kana.
| Japanese | Romaji | Meaning |
|---|---|---|
| 書く | kaku | To write, dictionary form |
| 書きます | kakimasu | The kanji is fixed; the kana changes |
| 書いた | kaita | Past |
| 書かない | kakanai | Negative |
| 書ける | kakeru | Potential |
| 書こう | kakō | Volitional |
In every form the kanji is unchanged. Everything that conjugates is in the kana, which is exactly what okurigana is for.
Where it fixes the reading
The more surprising job okurigana does is telling you which reading a kanji takes. Several kanji are used for more than one verb, and the position of the kana boundary is what separates them.
This means the boundary is part of the spelling. Writing it in the wrong place is not a small inaccuracy; it can produce a different word.
| Japanese | Romaji | Meaning |
|---|---|---|
| 上がる | agaru | To rise, intransitive |
| 上げる | ageru | To raise, transitive |
| 下がる | sagaru | To go down |
| 下げる | sageru | To lower |
| 起きる | okiru | To get up |
| 起こす | okosu | To wake someone |
The general rules
The conventions are regular enough to state, though there are exceptions to each. The core principle is that the kana begins at the point where the word starts changing.
Adjectives follow a similar logic, with the kana carrying the inflecting ending.
| Word type | Where the kana starts | Example |
|---|---|---|
| Godan verbs | At the final syllable | 読む |
| Ichidan verbs | At the syllable before the ending | 食べる |
| i-adjectives | At the final i | 高い |
| na-adjectives | Usually none | 静か |
| Adverbs from adjectives | Follows the adjective | 高く |
| Nouns from verbs | Often dropped | 話 |
The last row is a common source of confusion: a noun derived from a verb frequently loses its okurigana entirely.
The pairs worth memorising
A set of common verbs are distinguished only by okurigana, and mixing them up produces sentences that are grammatical and wrong. They are worth learning as explicit pairs.
Most of these are transitive and intransitive partners, which is a distinction Japanese marks far more systematically than many languages.
| Japanese | Romaji | Meaning |
|---|---|---|
| 開く / 開ける | aku / akeru | To open, intransitive and transitive |
| 閉まる / 閉める | shimaru / shimeru | To close, both |
| 始まる / 始める | hajimaru / hajimeru | To begin, both |
| 集まる / 集める | atsumaru / atsumeru | To gather, both |
| 変わる / 変える | kawaru / kaeru | To change, both |
| 決まる / 決める | kimaru / kimeru | To decide, both |
The pattern is visible: the intransitive tends to take a form ending in aru and the transitive one ending in eru. It is not universal and it is a useful hint.
Variant spellings
A small number of words have more than one officially permitted okurigana, so you will meet the same word spelled two ways. Both are correct and neither is an error.
For a learner the practical guidance is to pick one and be consistent within a document, and to recognise the other when reading.
| Japanese | Romaji | Meaning |
|---|---|---|
| 行う / 行なう | okonau | Both spellings are permitted |
| 表す / 表わす | arawasu | Both are seen |
| 申し込む / 申込む | mōshikomu | Compound verbs vary |
| 受け付ける / 受付ける | uketsukeru | Both occur |
| 取り扱い / 取扱い | toriatsukai | Nouns from compounds vary |
| 申込書 | mōshikomisho | In set nouns, often dropped entirely |
Learning it as part of the word
The efficient approach is to stop treating okurigana as a separate topic and learn it as part of each word. When you learn a verb, learn where the kana starts, in the same breath as the reading and the meaning.
That costs nothing extra and prevents the specific error of knowing a kanji, knowing a verb, and writing the boundary in the wrong place.
For the transitive and intransitive pairs, learn both together. They are the highest-value case and the one where the boundary carries the most meaning.
If you write a verb and are unsure where the kana starts, you have learned the kanji without the word. Look up the whole word rather than the character.