Chapter 3 — は vs が: Contrastive Analysis

Chapters 1 and 2 examined は and が separately, each on its own terms. You now understand what each particle does individually: は marks topics, creates contrast, and signals old information; が introduces new information, exhaustively identifies, and marks subjects inside subordinate clauses. This chapter puts them together and shows you what happens when the choice between them changes the meaning of an otherwise identical sentence.

This is the chapter that ties everything together. It is also the chapter that requires the most patience, because the differences between は and が are sometimes clear-cut and sometimes genuinely ambiguous. Native speakers do not always agree on which particle sounds better in a given context, and the "rules" are more like strong tendencies than absolute laws. We will be honest about where the lines blur.

Use the following flowchart as a quick decision guide when choosing between は and が:

は vs が: Quick Decision Guide
──────────────────────────────

  ┌──────────────────────────────┐
  │ Is this the FIRST mention of │
  │ the subject? (new info)      │
  └──────────────┬───────────────┘
                 │
         Yes ←───┴───→ No
          │              │
     ┌────┴────┐   ┌────┴─────────────────┐
     │ Use が   │   │ Is the speaker        │
     │         │   │ contrasting this with  │
     │ 猫が    │   │ something else?        │
     │ いる！  │   └────┬──────────────────┘
     └────────┘        │
                Yes ←───┴───→ No
                 │              │
          ┌──────┴──────┐  ┌───┴────────────┐
          │ Use は       │  │ Is this the    │
          │ (contrastive)│  │ topic of the   │
          │              │  │ sentence?      │
          │ 魚は 食べる   │  └───┬────────────┘
          │ (けど…)      │      │
          └─────────────┘  Yes ←┴→ No
                            │       │
                     ┌──────┴──┐  ┌─┴──────────┐
                     │ Use は   │  │ Use が      │
                     │ (topic)  │  │ (exhaustive │
                     │          │  │  or neutral) │
                     │ 猫は     │  │              │
                     │ かわいい │  │ だれが 来た？ │
                     └─────────┘  └─────────────┘

3.1 Information-Structure Framework: は = Old/Known, が = New/Unknown

The single most useful framework for choosing between は and が is the old-information / new-information distinction.

The principle

• は marks the element the speaker treats as already known to the listener — something shared, established, or presupposed. The new information is in the comment that follows は.
• が marks the element that is itself the new information — the thing being identified, announced, or introduced.

In a は sentence, the new information is in the predicate:

田中さんは先生です。 The listener already knows who Tanaka is. The new information is that he's a teacher.

In a が sentence, the new information is in the subject:

田中さんが先生です。 The listener already knows someone is a teacher. The new information is that it's Tanaka.

Where the new information falls

This framework predicts that は and が distribute new information differently:

With は, you know the topic and are learning the comment. With が, you know the predicate and are learning the subject.

This is why が appears naturally in answers to "who" and "what" questions:

誰が来ましたか。→ 田中さんが来ました。

The predicate 来ました ("came") is known — the question establishes it. What is unknown is the identity of the person. The answer provides that identity with が.

And this is why は appears when the topic is established and new information is in the comment:

田中さんはどこに行きましたか。→ 田中さんは大阪に行きました。

Tanaka is known — the question establishes him as the topic. What is unknown is where he went. The answer provides that information in the comment.

A test you can apply

When deciding between は and が, ask yourself: "What is the listener learning from this sentence?"

• If the listener is learning something about a known entity → は
• If the listener is learning which entity matches a known description → が

This test works in the majority of cases. It does not cover every situation (Sections 3.4 and 3.5 address the harder cases), but it is the most reliable starting point.

3.2 Same Sentence with は vs が — Meaning Shifts

The clearest way to understand the は/が distinction is to see the same sentence with each particle and observe how the meaning changes.

猫はいる vs 猫がいる

猫はいる。 "The cat is here." / "As for the cat, it exists." (topic: the cat; comment: it's here)

Implication: You asked about the cat, or we were talking about the cat. I'm telling you about the cat's status. There may be a contrast: the cat is here (but the dog isn't, or the cat is here but it's doing something problematic).

猫がいる。 "There's a cat." / "A cat is there." (new information: a cat exists in this location)

Implication: I'm noticing or announcing the presence of a cat. Maybe I just saw it. Maybe you didn't know there was one. The cat is the new piece of information.

誰が来た vs 誰は来た

誰が来た？ "Who came?" (asking for identification of the new-information subject)

？ 誰は来た？ This is ungrammatical in most contexts. は marks known information, but 誰 ("who") is inherently unknown — you cannot topicalize something you cannot identify. This is why question words like 誰, 何, どこ almost always pair with が, not は.

The exception is contrastive は:

誰は来て、誰は来なかった？ "Who came, and who didn't come?"

Here, は creates contrast. But this is a special construction, not the normal pattern.

田中さんは学生です vs 田中さんが学生です

田中さんは学生です。 "Tanaka is a student." (neutral statement — Tanaka is the topic, being-a-student is the news)

田中さんが学生です。 "Tanaka is the student." (identification — someone in this group is the student, and I'm telling you it's Tanaka)

The は version answers: "What is Tanaka?" The が version answers: "Which one is the student?"

水は飲んだ vs 水が飲みたい

水は飲んだ。 "Water, I drank." (contrastive は — I drank water, implying: but not something else, or: water at least)

水が飲みたい。 "I want to drink water." (water is the が-marked object of the stative predicate 飲みたい — see Section 2.3 for が with stative predicates)

雨は降っている vs 雨が降っている

雨は降っている。 "The rain is falling." / "As for the rain, it's falling." (topic — the rain was already being discussed, or the speaker is confirming its status)

雨が降っている。 "It's raining." / "Rain is falling." (new observation — the speaker is reporting or noticing the rain)

The が version is what you say when you look outside and see rain for the first time. The は version is what you say when someone asks about the rain, or when you want to talk about the rain's current status.

Summary table

3.3 Question-Answer Pairs: が in Questions Maps to が in Answers

One of the most reliable patterns in Japanese is this: the particle used for the unknown element in a question should be used for the corresponding element in the answer.

Who/what questions use が → answers use が

誰がパーティーに来る？ "Who is coming to the party?"

田中さんと山田さんが来る。 "Tanaka and Yamada are coming."

The が in the question marks the unknown subject (who). The が in the answer marks the now-identified subject (Tanaka and Yamada). Using は in the answer would change the nuance:

田中さんは来る。 "As for Tanaka, he's coming." (but what about the others? — this sounds like a partial answer with a contrast)

What-about questions use は → answers use は

田中さんは何を持ってくる？ "What is Tanaka bringing?"

田中さんはケーキを持ってくる。 "Tanaka is bringing cake."

The は marks the topic in both question and answer. The new information is in the comment (what he's bringing), not in the subject.

Which-one questions

どの本がおもしろかった？ "Which book was interesting?"

この本がおもしろかった。 "This book was interesting." (this one = the one)

The が is doing exhaustive identification: "This one, out of all of them."

Existence questions

冷蔵庫に何がある？ "What's in the refrigerator?"

牛乳と卵たまごがある。 "There's milk and eggs."

Again, が marks the newly identified items. If the answer used は:

牛乳はある。 "Milk, there is." (implying: but maybe not other things you wanted)

The は version partially answers the question and adds a contrastive shade.

The principle as a diagnostic

If you are unsure whether to use は or が, try constructing the question that your sentence answers:

• If your sentence answers "Who/what did X?" → use が
• If your sentence answers "What about X?" → use は

This is not a universal solution, but it is a practical tool for many common cases.

3.4 Thematic は across Paragraphs — Discourse Coherence

は does not only operate within a single sentence. One of its most important functions is at the discourse level: maintaining a topic across multiple sentences, tying a paragraph together into a coherent unit.

Topic continuity

When a writer or speaker establishes a topic with は, that topic remains active until a new topic is introduced. Subsequent sentences can omit the topic entirely, and the listener understands that the original topic is still in force:

田中さんは去年東京に引っ越した。新しいアパートは駅から近くて便利だそうだ。毎日電車で会社に通っている。週末は近くの公園で走っているらしい。

Translation: "Tanaka moved to Tokyo last year. The new apartment is apparently close to the station and convenient. [He] commutes to the company by train every day. On weekends, [he] apparently runs in a nearby park."

Notice that 田中さん appears only in the first sentence. Every subsequent sentence is still about Tanaka — the topic set by は in the first sentence carries through. Japanese permits this kind of sustained topic without repetition far more readily than English does.

Topic shift

When the writer wants to change topics, a new は signals the shift:

田中さんは東京に住んでいる。毎日忙しく働いている。 山田さんは大阪に住んでいる。のんびりした生活をしている。

The first は establishes Tanaka as the topic. The second は (山田さんは) signals that we are now talking about someone else. The reader instantly knows the frame has changed.

は as a paragraph organizer

In well-structured Japanese writing, は marks the topic of each paragraph or section, creating a clear organizational structure:

• Paragraph 1: 東京は ... (about Tokyo)
• Paragraph 2: 大阪は ... (about Osaka)
• Paragraph 3: 京都は ... (about Kyoto)

Each は sets the frame for its paragraph. Readers can use these は-markers as signposts, quickly identifying what each section is about.

When topics nest

Sometimes a topic is established for a large section, and smaller topics are established within it:

日本の教育は独特だ。小学校は六年間で、子どもたちは毎日給食を食べる。中学校は三年間で、部活動が重要になる。

"Japanese education is distinctive. Elementary school is six years, and children eat school lunch every day. Middle school is three years, and club activities become important."

The outer topic (日本の教育) is set in the first sentence. The inner topics (小学校, 中学校) are set in subsequent sentences, each providing details within the larger frame.

が breaks topic continuity

When が appears in the middle of a は-organized passage, it signals something new entering the scene:

田中さんは毎日同じカフェに行く。いつも同じ席に座って、コーヒーを飲む。ある日、知らない女の人が隣に座った。

"Tanaka goes to the same cafe every day. [He] always sits in the same seat and drinks coffee. One day, an unknown woman sat next to [him]."

The passage is organized around Tanaka (は topic). But in the third sentence, a new character appears — 知らない女の人 — and she takes が because she is new information being introduced into the narrative. After this introduction, if the passage continues to talk about her, she might take は in subsequent sentences.

This interplay between は (maintaining the frame) and が (introducing new elements within the frame) is how Japanese prose creates narrative flow.

3.5 Where the Rules Break or Blur

The framework presented in the previous sections — は for old information/topic, が for new information/identification — is the best general guide available. But it does not cover every case, and there are situations where native speakers disagree or where either particle sounds acceptable. Honesty about these gray areas is more useful than false certainty.

Generic statements

犬は賢い動物だ。 "Dogs are intelligent animals."

犬が賢い動物だ。 "Dogs are (the) intelligent animals."

The は version is a general statement about dogs as a category. The が version sounds like it is identifying dogs specifically as the intelligent animals (as opposed to other animals). In most contexts, は is the natural choice for generic statements. But in contrastive contexts ("Is it cats or dogs that are intelligent?"), が would be natural.

Emotional exclamations

きれいな花が咲いている！ "Beautiful flowers are blooming!"

きれいな花は咲いている。 "Beautiful flowers are (indeed) blooming."

In exclamations — sudden observations, emotional reactions — が is strongly preferred because the speaker is reporting a fresh perception. The は version sounds reflective or contrastive, not spontaneous. This is why descriptions of scenery, weather, and sudden events tend to use が.

First sentence of a passage

The opening sentence of a text often faces a choice: should the main entity take は (establishing it as the topic) or が (introducing it as new)?

日本は四季がある美しい国だ。 (は: setting up Japan as the known topic for what follows) 日本が四季がある美しい国だと、多くの外国人は言う。 (が: identifying Japan as the one that matches the description)

Both are possible. The choice depends on what comes next and on the speaker's rhetorical intent. There is no single correct answer.

After ～のは / ～のが

When a nominalized clause (の or こと) is the subject or topic, the choice between は and が follows the usual principles but can be subtle:

驚いたのは、彼が何も言わなかったことだ。 "What surprised me was that he said nothing." (は: the surprising thing is the topic; the content is the comment)

驚いたのが、彼が何も言わなかったことだ。 "What surprised me was that he said nothing." (が: identifying which thing surprised me)

Both are grammatical. The は version sounds more reflective; the が version sounds more immediate. In practice, both are common.

When は sounds wrong but が also sounds wrong

There are occasional sentences where neither particle feels perfectly natural, and native speakers might restructure the sentence entirely. For example, when introducing yourself in a group:

田中と申します。 (No particle at all — just the name followed by the verb)

Sometimes the best choice is neither は nor が, but restructuring. Japanese offers many ways to avoid the は/が decision, including omitting the subject entirely, using the copula differently, or rephrasing.

The honest conclusion

If you apply the old/new framework and the question-answer test from Section 3.3, you will choose correctly about 85-90% of the time. The remaining 10-15% involves contextual nuance, personal style, and genuine ambiguity. Do not be discouraged by this. Even native speakers occasionally pause over は/が choices in writing, and variation between speakers is normal. The goal is not perfection — it is developing intuitions strong enough that the unclear cases stand out as unclear, rather than every case feeling equally mysterious.

3.6 Extended Reading Passage — Analyzing は/が Choices

ある留学生の一日

リサさんはアメリカから来た留学生で、今東京の大学に通っている。日本に来てからもう半年になるが、毎日が新しい発見の連続だ。

朝は早い。七時に目覚まし時計が鳴ると、すぐに起きる。朝ごはんはいつもパンとコーヒーだ。日本の朝ごはんは魚や味噌汁が出ると聞いていたが、リサさんは朝からそんなにたくさんは食べられない。パンだけは毎日食べる。

大学まではバスで三十分かかる。バスの中では本を読むことが多い。最近読んでいるのは、日本の歴史についての本だ。漢字が難しくて、辞書を引きながら読んでいるが、内容はとてもおもしろい。

大学に着くと、まず図書館に行く。授業は十時からだが、その前に予習をするのがリサさんの習慣だ。図書館は静かで、集中できる場所だ。時々、知らない学生が隣に座ることがある。話しかけてくれる人もいるが、日本語で自分の気持ちをうまく伝えるのは、まだ難しい。

授業が終わると、友達とカフェに行くことが多い。日本語が上手な友達は韓国から来たキムさんだ。キムさんは漢字が読めるので、リサさんはいつもうらやましいと思っている。英語はリサさんのほうが得意だから、お互いに教え合っている。

夜はアパートに帰って、宿題をする。窓の外からは電車の音が聞こえる。東京は夜でもにぎやかだ。アメリカの田舎町とは全然違う。でも、この街が好きだ。毎日いろいろなことがあって、退屈することはない。

来月は春休みで、京都に行く予定だ。京都には古いお寺がたくさんあると聞いている。どんなところか、今からとても楽しみだ。

Translation

Lisa is an exchange student from America, currently attending a university in Tokyo. It has been half a year since she came to Japan, but every day is a continuous stream of new discoveries.

Mornings are early. When the alarm clock rings at seven, she gets up immediately. Breakfast is always bread and coffee. She had heard that Japanese breakfasts include fish and miso soup, but Lisa cannot eat that much from the morning. Bread, at least, she eats every day.

It takes thirty minutes to the university by bus. On the bus, she often reads books. What she is reading recently is a book about Japanese history. The kanji are difficult, and she reads while looking things up in the dictionary, but the content is very interesting.

When she arrives at the university, she first goes to the library. Classes start at ten, but studying before that is Lisa's habit. The library is quiet — a place where she can concentrate. Sometimes an unknown student sits next to her. There are people who strike up conversation, but conveying her feelings well in Japanese is still difficult.

When classes end, she often goes to a cafe with friends. The friend who is good at Japanese is Kim, who came from Korea. Because Kim can read kanji, Lisa always thinks how envious she is. English is something Lisa is better at, so they teach each other.

In the evening, she returns to her apartment and does homework. From outside the window, the sound of trains can be heard. Tokyo is lively even at night. It is completely different from her rural town in America. But she likes this city. Various things happen every day, and she is never bored.

Next month is spring break, and she plans to go to Kyoto. She has heard that Kyoto has many old temples. She is very much looking forward to seeing what kind of place it is.

は/が Analysis

This passage provides an excellent map of how は and が alternate in natural Japanese prose. Let us trace the key choices:

Paragraph 1:

• リサさんは — establishing the main topic of the entire passage.
• 毎日が新しい発見の連続だ — 毎日 takes が because the sentence identifies what each day is (exhaustive が with a copula-like structure). It answers "What is each day like?" not "What about each day?"

Paragraph 2:

• 朝は早い — 朝 is topicalized; the passage shifts to mornings.
• 目覚まし時計が鳴ると — inside a conditional clause (と), the subject takes が (Section 2.4).
• 朝ごはんはいつもパンとコーヒーだ — breakfast is topicalized.
• 魚や味噌汁が出る — inside a reported-speech clause (と聞いていた), が marks the subject.
• そんなにたくさんは食べられない — は on the degree expression with negation (Section 1.4 — negated elements take は).
• パンだけは毎日食べる — contrastive は: bread at the very least.

Paragraph 3:

• 大学までは — までは: topicalized endpoint (Section 1.6).
• 漢字が難しくて — が with a stative predicate (difficult).
• 内容はとてもおもしろい — contrastive は: the content (as opposed to the kanji) is interesting.

Paragraph 4:

• 授業は十時からだ — topicalized.
• 予習をするのがリサさんの習慣だ — が identifies what Lisa's habit is (exhaustive).
• 知らない学生が隣に座る — new person appearing: が for new information.
• 自分の気持ちをうまく伝えるのは、まだ難しい — the nominalized action is topicalized; the comment is that it's still difficult.

Paragraph 5:

• 授業が終わると — inside a temporal conditional (と), が marks the subject.
• 日本語が上手な友達はキムさんだ — が with the stative predicate 上手; は on the overall topic (the friend).
• 漢字が読めるので — が with the potential predicate 読める, inside a reason clause (ので).
• 英語はリサさんのほうが得意だ — contrastive は on English; が with 得意.

Paragraph 6:

• 電車の音が聞こえる — が with the perception verb 聞こえる (Section 2.3).
• 東京は夜でもにぎやかだ — topic.
• この街が好きだ — が with the stative predicate 好き.
• いろいろなことがあって — が with ある (existence).
• 退屈することはない — は with negative (Section 1.4).

Paragraph 7:

• 古いお寺がたくさんある — が with ある inside a reported clause.

Every single は and が in this passage follows the principles discussed in Chapters 1-3. There are no exceptions or anomalies. This is what natural Japanese looks like when you understand the system.

3.7 Vocabulary List