としたら・
Setting up hypothetical situations
Choose by asking what you are doing with the imagined situation. You may simply adopt it as a premise, treat it as a new reality with practical consequences, express a wish that is probably impossible, or warn that an attempted action would cause serious trouble. These are four different viewpoints, even though English can translate all of them with “if.”
Choose the operation, not the English translation
The words immediately before the ending provide the most useful clue.
Adopt a premise for reasoning
Plain statement + としたら・とすれば・とすると
You want to say “suppose this is true” and then calculate, judge, plan, infer, or ask what follows.
The premise need not be unlikely. Context, not the form alone, shows how realistic it is.
Consider a situation becoming real
Plain clause or noun + となったら・となれば・となると
You are reassessing duties, difficulties, plans, or expectations once a major situation actually comes about.
Keep the middle な; without it, you return to the family that merely sets up an assumption.
Express a remote wish
Potential verb + ものなら
The speaker would like something to be possible but sees it as exceptionally difficult, unlikely, or impossible.
This is too dramatic for an ordinary realistic condition.
Warn about a dangerous attempt
Volitional form + ものなら
Attempting the action—or even allowing the event to occur—would trigger punishment, damage, scandal, failure, or another serious result.
The volitional form here presents a dangerous possibility; it does not state an ordinary intention.
Merely suppose it, or deal with it as real?
A company may begin operating at night next month.
会社が来月から夜間営業を始めるとすると、必要な人員を計算し直さなければならない。
Assuming the company begins operating at night next month, we will have to recalculate the staffing requirements.
AnalyzeThe change is a premise used for calculation.
会社が来月から夜間営業を始めるとなると、勤務表をすぐに組み直す必要がある。
If the company really is going to begin operating at night next month, the work schedule will need to be redone immediately.
AnalyzeThe speaker treats the change as a new reality and turns to the practical response.
Takeaway: とすると says “use this as an assumption.” となると says “once this becomes the case, here is what changes.”
The verb form before the same ending reverses the stance
Before ものなら, a potential verb leads to a remote desire: “if I could.” A volitional form—the form normally used for “let’s” or “I will”—instead sets up a warning: “if someone were to attempt this.” The second clause should make the difference unmistakable.
あの日に戻れるものなら、別の言葉を選びたい。
If I could return to that day, I would choose different words.
AnalyzeThe potential verb introduces an unrealizable wish.
ここで計画を変更しようものなら、全体の納期に間に合わなくなる。
If we were to try to change the plan now, we would miss the overall deadline.
AnalyzeThe volitional form introduces an attempted action whose consequence makes the sentence a warning.
More examples across the family
仮に参加者が五十人だとすれば、椅子をあと十脚用意する必要がある。
Assuming there are fifty participants, we need to prepare ten more chairs.
Analyzeこの証言が正しいとしたら、事件の時刻を見直す必要がある。
If this testimony is correct, we need to reconsider the time of the incident.
Analyze彼女が次の責任者となれば、審査の方針も変わるかもしれない。
If she becomes the next person in charge, the review policy may change as well.
Analyze実際に支店を閉じるとなったら、利用者への案内を急がなければならない。
If the branch really is to be closed, we will have to notify its users quickly.
Analyze失った写真を取り戻せるものなら、どんな手間でもかけたい。
If I could recover the lost photographs, I would go to any amount of trouble.
Analyze一日だけ透明になれるものなら、誰にも気づかれずに町を歩いてみたい。
If I could become invisible for just one day, I would like to walk through town without anyone noticing.
Analyzeこの薄い氷の上を走ろうものなら、すぐに割れてしまう。
If anyone were to try running on this thin ice, it would break immediately.
Analyze顧客のデータを外部に送ろうものなら、重大な規則違反になる。
If anyone were to send customer data outside the organization, it would constitute a serious violation of the rules.
Analyze