We already know は marks the topic (私は学生です) and を marks the object (コーヒーを飲みます). But there's a common move in Japanese: swapping を for は to promote an object into the sentence's topic. This subtly shifts the focus of the sentence.
A Side-by-Side Comparison
A: どこで昼ごはんを食べますか。 → Where do you eat lunch?
B: 昼ごはんはどこで食べますか。 → As for lunch, where do you eat it?
Both ask about where to eat lunch, but the emphasis differs:
| Sentence | Structure | Focus |
|---|---|---|
| どこで昼ごはんを食べますか | Normal word order, を marks object | Focus is on "where" |
| 昼ごはんはどこで食べますか | Lunch promoted to topic with は | Focus is on "lunch" as a topic |
Sentence B means: "Speaking of lunch — where do you eat?" It announces the topic first, then asks for details.
Why Promote a Topic?
Japanese conversations often need to "announce the topic" — letting the listener know "what we're about to talk about" before diving into details. This is the core function of は.
Consider this scenario:
You and a friend are planning today's schedule. Breakfast is done, and you're now thinking about lunch.
Saying 昼ごはんは feels natural here — you're declaring "now we're talking about lunch," then asking "where shall we eat?"
If a waiter is simply asking you "where would you like to dine?", the direct どこで食べますか works better — no need to promote anything to a topic.
More Examples
| Normal Order (を) | Topic Promotion (は) |
|---|---|
| コーヒーを飲みます。 I drink coffee. | コーヒーは飲みます。 As for coffee, I drink it. |
| 映画を見ますか。 Do you watch movies? | 映画は見ますか。 As for movies, do you watch them? |
| 日本語を勉強しません。 I don't study Japanese. | 日本語は勉強しません。 As for Japanese, I don't study it. |
Notice the last example: 日本語は勉強しません implies "I don't study Japanese (but I might study other languages)." This is another characteristic of は — it often hints at a contrast: "as for this one... (but others might be different)."
は Replaces を
When は takes over from を, the を disappears — you cannot write 「昼ごはんをは」. は attaches directly to the noun:
| Original | After Promotion | Wrong |
|---|---|---|
| 昼ごはんを食べます | 昼ごはんは食べます | |
| コーヒーを飲みます | コーヒーは飲みます |
However, other particles like で, に, へ can stack with は:
教室では勉強します。 → As for in the classroom, I study. 日曜日には休みます。 → As for Sundays, I rest.
Only を and が get fully replaced by は. Other particles stack (では, には, etc.).
Practical Dialogue
A: 今日の晩ごはんはどうしますか。 → What shall we do about tonight's dinner?
B: 晩ごはんは外で食べましょう。 → As for dinner, let's eat out.
A: じゃ、飲み物はどうしますか。 → Then what about drinks?
B: 飲み物はいりません。 → As for drinks, we don't need any.
See the pattern? Every time the conversation shifts to a new topic, は introduces it. This is the rhythm of Japanese conversation.
Summary
- を marks the action's object; は marks the sentence's topic
- Swapping を for は promotes the object to a topic — "as for X, ..."
- When は replaces を, the を disappears (they don't stack). は and で/に/へ can stack (では, には)
- Topic promotion with は often carries a contrastive nuance: "this one... (but others might be different)"
Practice Quiz
Q1. What does 「コーヒーは飲みますが、紅茶は飲みません。」 mean?
Show Answer
I drink coffee, but I don't drink tea.
The two は create a contrast: coffee (drink) vs. tea (don't drink). This is exactly the contrastive function of は.
Q2. Translate "Where do you buy books?" into Japanese (normal word order). Then rewrite it with "books" promoted to the topic.
Show Answer
Normal order: どこで本を買いますか。 Topic promotion: 本はどこで買いますか。
The second sentence means: "As for books, where do you buy them?" The topic "books" is announced first.
Q3. Which sentence implies "I might study other subjects, but not math"? A. 数学を勉強しません。 B. 数学は勉強しません。
Show Answer
B. 数学は勉強しません。
は carries a contrastive nuance, implying "as for math, I don't study it (but other subjects might be a different story)." Sentence A is a simple statement: "I don't study math."