Two question families live on this page. どう builds manner questions — "how, in what way, how about." And a trio — なんで / どうして / なぜ — builds reason questions, all meaning "why." English hands you one word for each ("how," "why"), so two things surprise English speakers: Japanese splits "how" into どう versus どんな, and it offers three "why" words that differ not in meaning but in register. There is also a deeper pattern worth catching early: a "why" question is not a neutral request for a fact — it reaches for an explanation, which is why these questions and their answers travel as a matched pair (〜の？ … 〜から / んです).
どう — how, in what way, how about
どう is the adverbial "how." It asks about manner, means, or your impression of something, and it modifies verbs or sits before です to request an evaluation. Its most common jobs:
- Impression — どうですか / どうでしたか ("how is it? / how was it?")
- Means / method — どうやって, どうすれば ("in what way / how should I…")
- Suggestion — 〜はどう？ / 〜でもどう？ ("how about…?")
このスープ、どうやって作るんですか。
kono sūpu, dō yatte tsukuru n desu ka
How do you make this soup?
切符が買えないんですが、どうすればいいですか。
kippu ga kaenai n desu ga, dō sureba ii desu ka
I can't buy a ticket — what should I do?
新しいクラス、どう？
atarashii kurasu, dō?
How's the new class?
The last use — どう as a soft social invitation — has no clean English equivalent; we improvise with "how about…?":
ちょっと休憩して、お茶でもどう？
chotto kyūkei shite, ocha demo dō?
Let's take a break — how about some tea or something?
One caution, then a hand-off: どう is adverbial and can never attach to a noun with な (×どうな人). "What kind of _" is どんな + noun (どんな人 "what kind of person"). Because that split is really about the ど-series interrogatives, it is treated in full on どう・どんな・どうして; here we stay on question-building.
The three "why" words: a register ladder, not three meanings
Here is the insight that saves you a lot of grief: なんで, どうして, and なぜ all mean the same thing — "for what reason." They are not different questions. They are graded by register and tone, so choosing among them is a politeness decision, not a meaning one.
| Word | Register | Feel |
|---|---|---|
| なんで | casual, spoken | the everyday default with friends and family; can be blunt |
| どうして | neutral — speech and writing | safe middle ground; a touch of feeling, "how come" |
| なぜ | formal, written, academic | logical, detached — "for what reason"; stiff in casual chat |
なんで泣いてるの？
nande naiteru no?
Why are you crying? (casual)
どうして教えてくれなかったの？
dōshite oshiete kurenakatta no?
Why didn't you tell me?
なぜ日本では少子化が進んでいるのか。
naze nihon de wa shōshika ga susunde iru no ka
Why is the birth rate declining in Japan? (essay / news register)
Say なぜ to a friend and you sound like a written report or, worse, a cross-examination; say なんで in an essay and it reads as too casual. Match the word to the room. This register ladder is developed further, with more contrasts, on どう・どんな・どうして.
Why-questions come coupled to explanatory answers
This is the distinguishing point. A "why" question does not want a bare fact — it wants an explanation, and Japanese marks that explanatory mood grammatically on both sides of the exchange. On the question side, "why" questions very often end in の / のか (casual) or んですか (polite), which frame the utterance as "(tell me) the reason that…". On the answer side, the reason is delivered with 〜から or 〜ので ("because"), frequently closed by んです / のだ.
どうして遅れたの？
dōshite okureta no?
Why were you late?
ごめん、電車が遅れたから。
gomen, densha ga okureta kara
Sorry — because the train was delayed.
That の on the question and から on the answer are a matched pair: the の invites the explanation, the から delivers it. In polite speech the same coupling appears as んですか … んです:
どうして昨日、休んだんですか。
dōshite kinō, yasunda n desu ka
Why did you take yesterday off?
ちょっと熱があったんです。
chotto netsu ga atta n desu
I had a bit of a fever, that's why.
The "because" connectors themselves — から (subjective, speaker's reason) versus ので (softer, more objective) — are on から: because and ので: objective reason. The んです／のだ explanatory ending that so often closes these exchanges is the subject of のだ・んです.
In formal writing, the same explanatory framing surfaces as 〜のか, the reflective "the question of why…":
この実験がなぜ失敗したのか、もう一度考えてみよう。
kono jikken ga naze shippai shita no ka, mō ichido kangaete miyō
Let's reconsider why this experiment failed.
なんで also means "by what means" — a genuine ambiguity
Because なんで is written 何で, and 何で can also be read なにで ("by what means / with what"), the same string can ask why or how (by what). In speech, pitch and context sort it out; in writing, most people spell the "why" meaning in kana (なんで) and keep 何で for "by what means."
なんで会社まで来るの？
nande kaisha made kuru no?
Why do you come to the office? (why — reason)
The "by what transport" reading (careful なにで) is covered on 何: なに or なん. When you mean why, staying in kana (なんで) keeps you clear.
Common Mistakes
❌ 日本はどうな国ですか。
Incorrect — どう cannot attach to a noun with な. Use どんな + noun.
✅ 日本はどんな国ですか。
nihon wa donna kuni desu ka
What kind of country is Japan?
❌ （友達に）なぜ来なかったの？
Register-off — なぜ to a friend sounds stiff and accusatory, like an interrogation.
✅ なんで来なかったの？
nande konakatta no?
Why didn't you come? (natural casual)
❌ （レポートで）なんで景気が悪いのか。
Register-off — なんで is too casual for an academic essay.
✅ なぜ景気が悪いのか。
naze keiki ga warui no ka
Why is the economy weak? (formal / written)
❌ どうして遅れた？ ― 電車。
Under-answered — a why-question opens an explanation slot; a bare noun doesn't fill it. Give a 〜から reason.
✅ どうして遅れたの？ ― 電車が遅れたから。
dōshite okureta no? — densha ga okureta kara
Why were you late? — Because the train was delayed.
The first two are the classic traps: どう never becomes どうな (the pre-noun form is どんな), and the "why" word is a register dial, not a meaning switch. The last one is the coupling in action — answer a why-question with a reason, not a fragment.
Key Takeaways
- どう = how / in what way / how about; adverbial, never before a noun with な (that's どんな + noun). Polite/formal upgrade: いかが.
- なんで / どうして / なぜ all mean "why" and differ only by register: casual → neutral → formal.
- Pick the "why" word by who you're talking to, not by meaning.
- A why-question opens an explanation slot: it often ends in の／んですか and is answered with 〜から／〜ので (often + んです). Question and answer are a matched pair.
- なんで (何で) can also mean "by what means" — spell the "why" sense in kana to stay clear.
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- だれ / なに・なん / どこ / いつN5 — How to build who/what/where/when questions: drop the question word into the exact slot the answer would fill, give it the particle that slot demands, and mark the sentence — the word never moves to the front.
- から: Because (Speaker's Reason)N5 — から attaches to the end of the reason clause and states the speaker's own subjective reason or motivation, which makes it the assertive 'because' behind excuses, invitations, warnings, and commands.
- どう・どんな・どうして: How, What Kind, WhyN4 — How どう asks manner and impression, どんな asks what kind of noun, and the three 'why' words なぜ, どうして, and なんで split by register rather than meaning.
- のだ / んです: The Explanatory MoodN4 — One of Japanese's highest-frequency structures — のだ／んです frames a statement as an explanation, reason, or account of the situation rather than a bare fact.
- Asking Questions in Japanese: OverviewN5 — The big picture of Japanese questions — you never rearrange the sentence; you add か, raise your pitch, or drop a question word in place, and the same clause becomes a question.