万が一
Just in case, In the worst-case scenario, In the unlikely event, By any chance
Structure
Explanation
The expression 万が一, which can be shortened to 万一, signifies a 'one-in-ten-thousand' chance of something happening. It is used to talk about a highly improbable, hypothetical situation, similar to English phrases like 'on the off chance that (A)' or 'if, by some slim chance (A)'. The second half of the sentence will typically describe a precaution taken against (A) or a consequence that would follow (A).
万が一 generally functions as an adverb and is therefore most often placed at the start of a clause.
- 万が一のために、保険に入っておきました。I took out insurance, just in case.
- 万が一パスポートをなくした場合は、すぐに大使館へ行ってください。In the unlikely event that you lose your passport, please go to the embassy immediately.
Fun-fact
While 万が一 carries a slightly stronger sense of improbability than 万一, the longer form with が is used more frequently because it tends to be easier to say.
- 万が一の時のために、緊急連絡先を伺ってもよろしいですか。Could I get your emergency contact information, just in case?
- 万一データが消えてしまったら、すぐに教えてください。If by some chance the data gets deleted, please let me know right away.
Examples
万が一のために、懐中電灯を用意しておこう。
Let's prepare a flashlight, just in case.
(in the unlikely event...)
万が一パスワードを忘れた場合は、この質問に答えてください。
In the unlikely event you forget your password, please answer this question.
万が一この計画が失敗しても、代わりの案は準備してあります。
Even in the worst-case scenario that this plan fails, we have an alternative idea prepared.
万が一試合に負けても、私たちは君を誇りに思うよ。
Even in the unlikely event that you lose the match, we will still be proud of you.
万が一道に迷うと困るから、地図を持って行こう。
Since we'll be in trouble if we get lost, let's bring a map just in case.
(in the unlikely event...)
万が一、有名人になったら、世界中の恵まれない子供たちを助けたい。
By any chance, if I became famous, I would want to help underprivileged children around the world.
万が一電話に出られなかった場合は、メッセージを残してください。
Just in case I can't answer the phone, please leave a message.
(in the unlikely event...)
万が一システムにエラーが発生した場合は、すぐに技術サポートに連絡してください。
In the unlikely event a system error occurs, please contact technical support immediately.
万が一終電を逃したら大変なので、タクシー代も持っておこう。
It would be bad if we missed the last train, so let's bring some taxi money just in case.
(in the unlikely event...)
万が一鍵をなくしても家に入れるように、合鍵を作っておいた。
I had a spare key made so that I can get in the house, even in the worst-case scenario that I lose my key.
万が一合格しなかったら、また来年チャレンジするつもりです。
In the unlikely event that I don't pass, I intend to try again next year.
万が一のことが起きたら、すぐにこのボタンを押してください。
If an emergency occurs, please press this button immediately.