How to tell them apart
All four describe an event happening immediately after another, but they differ in register and what follows. 途端に is the most everyday and can follow actions or changes of state. や否や, なり, and が早いか are more literary/formal and tend to describe an immediate, often surprising or involuntary reaction. なり specifically attaches to a verb in plain form and stresses the first thing someone did right after, often a sudden personal action. が早いか emphasizes the speed with which the subject moves from one action to the next, typically with the same subject doing both. や否や is used for events that trigger an immediate, often large-scale or dramatic response.
- 途端（に） Use 途端に when you want a common, neutral way to say something happened the instant something else occurred.
- や否や・やいなや Use や否や in formal or written contexts to describe an immediate, often dramatic consequence right after an event.
- なり Use なり to stress the very first action someone took right after doing or experiencing something.
- が早いか Use が早いか to emphasize how quickly the same subject rushed into the next action without hesitation.
| Grammar point | Meaning | JLPT level |
|---|---|---|
| 途端（に） ni | the very instant something happens; right after doing something | N2 |
| や否や・やいなや ya ya yainaya | The instant something happens; immediately after | N1 |
| なり nari | The moment something happens; right after doing | N1 |
| が早いか ga ika | The instant something happens; right after it occurs | N1 |
途端（に） ni
the very instant something happens; right after doing something
途端に expresses that one event happens in the very instant a completed action occurs, often highlighting a sudden or unexpected result. It attaches to the plain past form of a verb, as in 聞いたとたんに or 触れたとたん, with に optional and no change in meaning. The second clause must describe something that actually happened and cannot express a command, request, or speaker intention.
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そのニュースを聞いたとたんに彼女は真っ青になった。
On hearing the news, she turned pale.
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女の子達は彼のジョークを聞いたとたんに笑い出した。
The girls burst into laughter when they heard his joke.
や否や・やいなや ya ya yainaya
The instant something happens; immediately after
や否や and やいなや express that a second action happened the instant after a first action, with a nuance of surprise or immediacy. They attach to the dictionary form of a verb, as in 見るやいなや or 到着するや否や, and the following clause is normally in the past tense. Both forms are formal and literary, with や否や sounding more stiff than やいなや, and they are not used for commands, requests, or the speaker's own intentional next action.
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彼を見るやいなや私は彼が怒っているのがわかった。
The instant I saw him I knew he was angry.
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その音を聞くやいなや、犬は逃げていきました。
On hearing the sound, the dog rushed away.
なり nari
The moment something happens; right after doing
なり expresses that one action follows immediately after another is completed, with a nuance of surprise or suddenness. It attaches directly to the dictionary form of a verb, as in 見るなり or 着くなり. It is a formal, written style expression, and the following clause usually describes a completed past event rather than a request, command, or intention.
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家に帰るなり、ベッドに倒れた。
As soon as I got home, I collapsed onto the bed.
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写真を見るなり、昔を思い出した。
The moment I saw the photo, I remembered the old days.
が早いか ga ika
The instant something happens; right after it occurs
が早いか expresses that a second action follows almost immediately after a first action, with no delay between them. It attaches to the dictionary form of a verb, as in 鳴るが早いか or 開くが早いか, and the main clause that follows is normally in the past tense. It is a formal written expression for N1 level, and the subject of the two clauses is often different.
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授業の終わりのベルが鳴るが早いか、生徒達は教室を出て行った。
As soon as the school bell rang, the students left the classroom.
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ドアが開くが早いか、犬が外へ走った。
The moment the door opened, the dog ran outside.
途端（に） and や否や・やいなや and なり and が早いか are JLPT N2–N1 grammar points that Japanese learners often mix up. This page compares all 4 side by side on meanings, usage and example sentences, so you can tell them apart.