〜と、〜
Conditional と (whenever / when)
Meaning
Two uses: (1) natural/habitual consequence — "whenever A happens, B happens"; (2) discovery — "when I did A, (I found that) B". The result B cannot be a volitional, request, or intention.
Formation
[plain form] + と、 + [result]
Notes
Cannot be followed by volitional/request/intention (×春になると、花見に行こう). For those, use たら or なら. Also used for "when (I did X), I discovered Y": 駅に着くと、友達がいた.
Examples
春（はる）になると、花（はな）が咲（さ）きます。
When spring comes, flowers bloom. (natural consequence)
Breakdown
このボタンを押（お）すと、ドアが開（ひら）きます。
When you press this button, the door opens.
Breakdown
右（みぎ）へ曲（ま）がると、駅（えき）があります。
When you turn right, there is a station.
Breakdown
窓（まど）を開（あ）けると、雪（ゆき）が降（ふ）っていました。
When I opened the window, I found it was snowing. (discovery)
Breakdown
夜（よる）になると、気温（きおん）が下（さ）がります。
When night comes, the temperature drops.
Breakdown
この薬（くすり）を飲（の）むと、眠（ねむ）くなります。
When you take this medicine, you get sleepy.
Breakdown
⚠️ Often confused with
〜ば
Conditional 〜ば (if / whenever)
A general conditional — "if A, then B". Formed from the hypothetical form (仮定形) of the...
〜たら
Conditional 〜たら (if / when / after)
The most versatile conditional. "If/when A happens, B". Formed from the ta-form stem + ら....
〜なら
Conditional 〜なら (if / given that)
A conditional based on the listener's stated or known information — "if it's the case that...
〜ても / 〜でも
Even if 〜ても
"Even if A, B" / "no matter if A". Indicates that B happens regardless of A. The result is...
〜場合は
In case 〜場合は
"In the event that ~ / in the case that ~". Used to discuss what to do in a particular (of...
〜ないことには
Unless 〜ないことには
"Unless ~", "without first ~ing" — nothing can proceed until this happens.
〜としたら / 〜とすれば
Supposing 〜としたら
"Supposing ~", "if we assume ~" — reasoning from a hypothetical.
〜てからでないと
Not until 〜てからでないと
"Not until ~", "unless ~ is done first" — a precondition that must come first.
〜さえ〜ば
If only 〜さえ〜ば
"If only ~", "as long as just ~" — one sufficient condition.