“〜to naru to・to nareba”: When It Comes to 〜 / Once 〜 (a situation that triggers a response) [JLPT N2]

Content by NTJ Kuma · Nihongo to Japan editorial team · Updated July 27, 2026

「子供のこととなると真剣になる」 — bring up that topic, and things predictably change.

「いざ本番となると、緊張する」 — once it really comes to that moment, things change

Calm as you normally are, 「いざ本番となると、緊張する」 (once it's really showtime, you get nervous) — 「〜となると・〜となれば」 = once ～ (a situation holds)／when it comes to ～, things will…, used to express “when a particular situation actually holds, or when a particular topic comes up, some result or reaction (naturally) follows.” It carries the sense of “(that being so,) things are different now, you have to take it seriously.” This guide covers its two uses, attachment, and how to separate it from the purely hypothetical 「とすると.」

Core: not an offhand hypothesis — ‘once it really comes to that' then…

「(noun／plain form) ＋ となると／となれば」 has two core uses:

① Once ～ (a situation is really about to hold):

• いざ本番となると、手が震える (once it's really showtime, my hands shake).
• 留学するとなると、かなりお金がかかる (when it comes to actually studying abroad, it costs quite a bit).

② When it comes to／whenever ～ (a particular topic or object):

• あの人のこととなると、彼は人が変わる (when it comes to that person, he becomes a different man).
• お酒のこととなれば、彼の右に出る者はいない (when it comes to sake, no one surpasses him).

Feel: “once ～ then…／when it comes to ～ then…” — the core is “when that particular situation actually holds (or the topic comes up), it naturally leads to some result,” and it often carries the reality-weight of “(now that／once it's come to this,) things are different, you have to take it seriously.” It's not an offhand hypothesis but “if it really comes to that….”

Forms & attachment

Examples in context

• 普段は無口だが、趣味の話となると、止まらなくなる。(Normally quiet, but when it comes to his hobby, he can't stop.)
• 家を買うとなると、簡単には決められない。(When it comes to actually buying a house, you can't decide easily.)
• 子供のこととなれば、親は必死になる。(When it comes to their children, parents become desperate.)
• いざ別れるとなると、やはり寂しい。(When it really comes to parting, it's sad after all.)
• 責任者がいないとなると、話が進まない。(If the person in charge is absent, things won't move forward.)

⚠️ Easy traps to avoid

① There are two uses: ‘once a situation holds' and ‘when it comes to a particular topic.' 「〜となると」 isn't just one meaning, and learners often remember only half. Use 1: once ～ (a situation is really about to hold) — stressing “when that situation becomes reality, then…”: いざ試験となると、頭が真っ白になる (once it's really the exam, my mind goes blank), 家を買うとなると、大きな決断だ (when it comes to actually buying a house, it's a big decision). Use 2: when it comes to／whenever ～ (a particular topic or object) — stressing “whenever the topic touches that, then (a special reaction)”: あの人のこととなると、彼女は感情的になる (when it comes to that person, she gets emotional). Both carry the flavor “hit that particular situation／topic, and a reaction naturally follows.” Test: if what precedes is “a (really-about-to-happen) situation” → Use 1; if it's “a topic／object that triggers a reaction on contact” → Use 2.

② Attach a noun or plain form ＋ となると／となれば. Get the attachment right. What precedes is a noun (本番・留学・子供のこと) or a plain form (verb dictionary form: 引っ越すとなると; i-adj: 安いとなると; noun だ: 本番だ→本番となると). It's the structure 「となる (become) ＋ と／ば,」 literally “once it becomes the situation of ～.” Mnemonic: (noun／plain form) ＋ となると／となれば = once ～ then／when it comes to ～ then.

③ 「となると」 vs 「とすると」: really comes to it (reality-weight) vs a pure hypothetical inference. These differ by one part, with different feels. 「〜となると」 = once ～ (really holds) then…: it carries the reality-weight, the sense of facing up, that “that situation is really about to happen／hold,” with a following “(that being so,) it naturally…”: 留学するとなると、ビザが必要だ (when it comes to actually studying abroad, you need a visa — really facing it). 「〜とすると／とすれば」 = supposing ～: a purer hypothetical inference, without the reality-weight of “really about to be so”: 彼が犯人だとすると、動機は何か (supposing he's the culprit, what's the motive — pure reasoning). Difference: 「となると」 is “(really) come to that situation → the natural result／having to face it”; 「とすると」 is “(pure hypothesis) if so → an inference.” Test: to express “(if it really／once it) comes to that, things then… (with reality-weight)” → となると; to express “(hypothetically) if ～, then… (logical reasoning)” → とすると.

🔄 Compare: となると／となれば／とすると／ともなると

💡 An exam judgment tip

「〜となると・〜となれば」 = once ～ (a situation really holds)／when it comes to ～, things will… — three points: ① there are two uses — “once a situation holds” (いざ本番となると = once it's really showtime, then…) and “when it comes to a particular topic” (あの人のこととなると = when it comes to that person, then…); ② attach a noun／plain form ＋ となると／となれば; ③ separate it from the purely hypothetical 「とすると」 — となると carries the reality-weight of “really about to be so, must face it,” while とすると is the pure inference “supposing ～.” This pattern is very everyday — 「〜となると、話は別だ (in that case, it's a different story),」 「〜となると、そう簡単にはいかない (when it really comes to that, it's not so simple)」 are super handy. It captures that turn where “normally it's nothing, but once you really hit that situation／topic, things are entirely different.”

❓ Quick FAQ

Q: 「となると」 and 「とすると」 both translate as ‘if ～' — how do I tell them apart?

The difference is ‘whether it carries reality-weight (really about to be so).' 「〜となると／となれば」 = once ～ (a situation really holds) then… (with reality-weight, facing up): it presupposes “that situation is really about to happen／hold,” or “when it comes to a particular topic,” with a following “(that being so,) it naturally…, you must face it seriously,” carrying real weight: 留学するとなると、費用が心配だ (when it comes to actually studying abroad, the cost is worrying — actually facing this), いざ本番となると、緊張する (once it's really showtime, you get nervous — the real moment). Its flavor is “(really) come to that point, and things are different.” 「〜とすると／とすれば」 = supposing ～ (pure hypothetical inference): it's a pure hypothesis, used to infer “if the premise holds, what follows,” without the reality-weight of “really about to be so,” mostly for logical reasoning: この数字が正しいとすると、来年は赤字だ (supposing this figure is right, next year is a deficit — pure calculation), 彼が来ないとすれば、予定を変えよう (supposing he won't come, let's change the plan — hypothetical). Difference: 「となると」 stresses “(really) come to that situation → the natural result／facing it” (reality-weight); 「とすると」 stresses “(hypothetically) if so → a logical inference” (hypothetical). Test: to say “(if it really／once it) comes to that, things then… (with the weight of facing reality)” → となると; to say “(pure hypothesis) if ～, then… (logical reasoning)” → とすると. E.g. 「結婚するとなると、いろいろ準備が要る (when it comes to actually marrying, lots of prep is needed — really facing it)」 uses となると; 「明日晴れるとすると、どこへ行こうか (supposing it's clear tomorrow, where shall we go — pure hypothesis)」 uses とすると.

Q: What does 「〜のこととなると」 mean? Why is it used so often?

「〜のこととなると」 is the high-frequency fixed pairing for 「となると」's second use (when it comes to a particular topic／object), meaning “when it comes to ～ (this topic／this person), a special reaction follows.” It stresses “the moment the topic touches that particular person or thing, someone shows a reaction unlike their usual self”: 食べ物のこととなると、彼は目の色が変わる (when it comes to food, his eyes change — super keen), お金のこととなると、急に真剣になる (when it comes to money, he suddenly gets serious), 我が子のこととなると、親バカになる (when it comes to their own child, they become a doting fool). Why 「のこと」 so often? — because this use hinges on “a particular topic domain／object,” and 「〜のこと (the matter of ～, regarding ～)」 is just right for marking off that topic scope, so “(person／thing) ＋ のこと ＋ となると” became a set phrase. It vividly depicts “ordinarily very plain, but the moment it touches that particular topic, the person is entirely different” — usually with a touch of exaggeration, teasing, or affection. To express “when it comes to so-and-so, someone acts a certain way,” 「〜のこととなると、〜」 is the most vivid.

🖊️ Practice Questions (5)

Q1. 「いざ発表___、急に不安になった。」（once it came to presenting, (I) suddenly became anxious）

(A) となると　(B) どころか　(C) ばかりに　(D) わりに

Q2. 「家を買う___、よく考えなければならない。」（when it comes to buying a house, (you) have to think carefully）

(A) となると　(B) ながらも　(C) ところで　(D) としても

Q3. 「子供のこととなると真剣になる」の意味は?

(A) The moment it's about the children, (one) becomes serious

(B) Nothing to do with children

(C) Not serious about children

(D) Children are annoying

Q4. 「となると」の語感として正しいのは?

(A) Once that situation holds, a corresponding consequence follows (fairly definite)

(B) A pure hypothesis, may not happen

(C) Indicates a reason

(D) Indicates contrast

Q5. 接法が正しいのは?

(A) 試験となると緊張する。　(B) 試験をとなると緊張する。

(C) 試験になるとなる緊張。　(D) 試験ととなると緊張。

Answer Explanations

1. (A) となると ── Once it comes to presenting (a triggering situation), (I) become anxious.

2. (A) となると ── When it comes to buying a house, (one) must be careful.

3. (A) ── The moment it's about the children, (one) becomes serious.

4. (A) ── Once the situation holds, a corresponding consequence follows (fairly definite).

5. (A) ── Noun directly ＋ となると; the other connections are wrong.