誰・どこ・いつ: Who, Where, When

Three question words come up in almost every conversation: 誰（だれ） "who," どこ "where," and いつ "when." They are easy to translate but they behave differently in one important way — the particles that follow them. 誰 and どこ take the same particles as any other noun, so mastering them doubles as particle practice. いつ, by contrast, quietly refuses one particle you'd expect. This page walks through all three and pins down exactly which particle goes where.

誰 — who

誰 is a noun, so it takes whatever particle the grammar of the sentence calls for: が for the subject, の for possession, に for the person affected, と for "with whom," を for the object.

Notice that 誰 slots into exactly the position and particle a name would take: 誰が来ますか → 田中さんが来ます; 誰に会いましたか → 友達に会いました. As always in Japanese, the question word doesn't move — see the question-words overview.

どこ — where

どこ is also a plain place-noun, and this is the key insight: どこ takes で, に, or へ by the very same rules as any location word. Choosing the right one is not a special "question-word rule" — it is the ordinary location-particle logic in question form.

• で — where an action happens (the venue of doing something)
• に — where something exists or ends up (existence, residence, destination)
• へ — the direction of movement (toward where)

Buying is an action → で. Living is existence/residence → に. Going is movement toward → へ (or に; both work for destinations). This is exactly the で/に/へ contrast you drill for statements; reviewing に vs で and に vs へ for destinations pays off directly here.

いつ — when

いつ means "when," and it has one quirk worth memorizing: いつ normally takes NO に. You ask いつ帰りますか, never ×いつに帰りますか.

Why no に? Because いつ belongs to the family of relative time words — the same class as 今日（きょう, today）, 明日（あした, tomorrow）, 毎日（まいにち, every day）— and those never take に either. You say 明日行きます, not ×明日に行きます. に attaches only to absolute, calendar-or-clock time points: 3時に (at 3:00), 月曜日に (on Monday), 2月に (in February). Since いつ ranges over the relative-time category, it inherits the no-に behavior of its class.

いつ does freely combine with から ("since when") and まで ("until when"), because those are not the に that's being blocked — they mark span, not a point.

From-where and how-far: どこから / どこまで

Because どこ is an ordinary place-noun, it also pairs with から ("from") and まで ("to / as far as"), which is how you ask about origins and endpoints of a journey or range:

And 誰 takes を when the person is the object of an action — a slot English keeps invisible:

Here 呼ぶ ("to invite / call") acts on the person, so 誰 is the direct object and takes を — exactly as a name would (田中さんを呼びます). Compare 誰に会う ("meet with someone," に) and 誰と行く ("go with someone," と): the particle you choose spells out the relationship, and 誰 simply inherits whatever the verb demands.

Building indefinites: + か / も / でも

Each of these three question words converts into an indefinite by adding か, も, or でも — a hugely productive pattern:

The full system — including why 誰も and どこも flip to "nobody/nowhere" with a negative verb — is on question words + か / も / でも.

Common Mistakes

The で/に contrast in the second and third pairs is the same one that governs every location noun: 住む ("reside") describes a state of existence → に, while 買う ("buy") is an action performed at a venue → で. Learn どこ well and you are really learning the location particles.

Key Takeaways

• 誰 (who), どこ (where), いつ (when) are ordinary nouns; 誰 and どこ take whatever particle the sentence's grammar requires.
• どこ takes で / に / へ by the normal location rules: で for actions, に for existence/destination, へ for direction. This page is really particle practice in disguise.
• いつ takes no に, because it belongs to the relative-time class (like 今日, 明日) that never uses に; only clock/calendar points take に.
• Add か / も / でも to make indefinites: 誰か・誰も・誰でも, どこか・どこも・どこでも, いつか・いつも・いつでも.
• Polite variants: 誰 → どなた, どこ → どちら.