Translation guide
Expresses that something happens at the very instant another action or state occurs. Often translated as 'the moment (that)...', 'as soon as...', or 'just when...'.
To say that B happens right after A, with no delay.
Used when B occurs immediately after A, often with a sense of suddenness or unexpectedness. A is usually a verb in the past plain form (た-form).
ドアを開けたとたんに猫が飛び出した。
The moment I opened the door, a cat jumped out.
He burst out laughing the moment he saw it.
A literary or formal pattern meaning 'no sooner had A than B'. A is a verb in the dictionary form.
彼は家に着くやいなや、また出かけた。
No sooner had he arrived home than he went out again.
Similar to やいなや, but slightly more colloquial. A is a verb in the dictionary form. Emphasizes the speed of the sequence.
彼は私の顔を見るが早いか、怒鳴り始めた。
The moment he saw my face, he started yelling.
Used when B happens immediately after A, and the subject of A and B is the same. A is a verb in the dictionary form. Often implies the action B is unexpected or unusual.
彼は部屋に入るなり、窓を開けた。
The moment he entered the room, he opened the window.
To emphasize that something happens precisely at that time, often with a nuance of coincidence or interruption.
Used when B occurs just at the moment A is about to happen, is happening, or has just happened. A is a verb in the dictionary form, ている form, or た form.
出かけようとしたところに電話が鳴った。
Just as I was about to leave, the phone rang.
ちょうど彼のことを考えていたところに、彼からメールが来た。
Just when I was thinking about him, I got an email from him.
Literally 'at the moment the arrow is shot', meaning 'just when A was about to happen, B (often something unexpected) occurred'. A is a verb in the volitional form + とした or とする.
家を出ようとした矢先に雨が降り出した。
Just as I was about to leave the house, it started raining.
Used when B happens accidentally or unexpectedly at the moment of doing A. A is often a verb in the た form or a noun + の.
転んだ拍子に眼鏡を壊してしまった。
I broke my glasses the moment I fell.
To indicate that a state or action has continued from a specific past moment.
Means 'ever since A happened, B has been the case'. A is a verb in the て form. B describes a continuing state or repeated action.
彼女に振られてからというもの、ずっと落ち込んでいる。
Ever since she dumped me, I've been depressed.
Literally 'with A as the turning point', meaning 'from the moment A happened, things changed to B'. A is a noun or verb phrase.
その事件を境に彼の人生は一変した。
His life changed completely from the moment of that incident.
とたんに is the most common and neutral for immediate sequence. やいなや is formal/literary. なり requires the same subject for both actions and often implies an unexpected second action.
Do not translate 'the moment' word-for-word as 瞬間 (しゅんかん) in these patterns. While 瞬間 can be used in some contexts, the patterns above are more natural for expressing immediate sequence.