Every beginner hits the same wall around week three of Japanese. You've learned that は (wa) is the topic particle. You've learned that が (ga) is the subject particle. Then you meet your first sentence like zou wa hana ga nagai — "as for the elephant, the nose is long" — and both particles appear in the same short sentence, and suddenly nothing your textbook said seems to help.
This guide fixes that. It's not another restatement of "は is topic, が is subject." It's a mental model you can actually use: what each particle is doing to the information around it, how to pick between them in the wild, and the five specific patterns where beginners almost always guess wrong.
TL;DR. は sets the stage — it says "here's what we're going to talk about." が puts a spotlight — it points at the specific thing doing the action or being described. If a question word (who? what?) is involved, if something new is being introduced, or if you're singling one thing out from several, use が. Otherwise, は is usually right.
1. Topic vs subject — what these words actually mean
English doesn't grammatically mark "topic" at all, which is why the concept feels slippery. Every English sentence has a subject (the person or thing doing the verb), but nothing forces you to say what the whole sentence is about up front. In Japanese, は does exactly that: it labels one noun as "the thing this whole sentence is going to comment on."
The subject, by contrast, is a grammatical role tied to the verb. It's whoever is running, eating, existing, being cold. In Japanese that role is marked by が. Often the topic and the subject are the same thing — but they don't have to be, and that's where the confusion starts.
私は学生です。
Watashi wa gakusei desu.
"As for me, [I am] a student." — The topic is "me". The comment is "student".
雨が降っています。
Ame ga futte imasu.
"It is raining." — Literally: "rain is falling." Rain is the subject of the verb 降る (fall). No topic is set — the sentence is a raw observation.
Notice what changed. The first sentence sets a topic and then describes it. The second one is a scene report — no framing, just a subject doing an action. That's the fundamental split: は frames, が points.
2. When to use は — the topic marker
Use は when the noun in front of it is shared context. Either the listener already knows what you're talking about (you're switching to it as a topic), or you're introducing yourself, or you're stating a general truth about a class of things.
田中さんは先生です。
Tanaka-san wa sensei desu.
"Tanaka is a teacher." (Tanaka is already known — you're commenting on him.)
猫は魚が好きです。
Neko wa sakana ga suki desu.
"Cats like fish." (General statement about cats as a category — followed by a subject inside.)
今日は月曜日です。
Kyou wa getsuyoubi desu.
"Today is Monday." (Today is the frame; Monday is the comment.)
Two more は uses worth knowing:
- Contrast. は quietly implies "as for this one, but maybe not others." Sushi wa suki desu. ("I like sushi" — with the unspoken subtext "…but not necessarily other things.")
- Negatives. は tends to appear in the negative half of a sentence to soften it: Kanji wa yomemasen. ("I can't read kanji" — as for kanji specifically, no.)
3. When to use が — the subject marker
が does three jobs that は cannot do. If you can spot which of the three you're in, the choice becomes automatic.
3a. Answering a question word
Question words like だれ (who), なに (what), どれ (which) always take が. There's a reason: は marks something the listener already knows, and a question word is by definition unknown. Same rule applies when the answer identifies unknown information.
だれが来ましたか。 — 田中さんが来ました。
Dare ga kimashita ka. — Tanaka-san ga kimashita.
"Who came? — Tanaka came." (Never は in either half.)
3b. Reporting something new — description, discovery, existence
When you notice something for the first time, or point out that something exists, or describe a scene, use が. It's the "look at this" particle.
あ、猫がいる！
A, neko ga iru!
"Oh, there's a cat!" (New information, discovery.)
机の上に本があります。
Tsukue no ue ni hon ga arimasu.
"There is a book on the desk." (Existence — always が, not は.)
3c. Singling one thing out — "exhaustive listing"
When you want to say "this one, specifically, and not the others," が puts a spotlight. Compare the pair below carefully — same words, different meaning, and the particle is the only thing that changes.
私は行きます。
Watashi wa ikimasu.
"As for me, I'll go." — Neutral, just stating your plan.
私が行きます。
Watashi ga ikimasu.
"I'll go." — With emphasis on me, as in "I'll be the one to go" (not you, not him).
4. Quick comparison table
| Situation | Particle | Why |
|---|---|---|
| Talking about yourself, family, work | は | Known topic — you're commenting on it |
| Answering "who / what / which" | が | Question words never take は |
| Something exists (あります / います) | が | New information about existence |
| Weather / natural events | が | Raw event, no topic being framed |
| Adjectives of feeling: 好き, 嫌い, 上手 | が | The thing you like/dislike is the が-subject |
| General truths about a category | は | You're setting up a topic for a claim |
| Subordinate clauses (relative, embedded) | が | は generally can't survive inside a sub-clause |
| Emphasis: "this one, specifically" | が | Spotlight on one item from a set |
5. Five traps beginners hit almost every time
5.1 Using は with question words
The most common single mistake. You'll want to say Dare wa kimashita ka? because "who" feels like the topic. It isn't — it's asking for new information, so が is required.
✗ だれは来ましたか。 — ungrammatical
✓ だれが来ましたか。 — "Who came?"
5.2 Forgetting が inside a relative clause
Inside a relative clause (the part that modifies a noun), は almost always switches to が. The sub-clause is describing which specific noun you mean, so it needs a subject marker.
私が読んだ本は面白かったです。
Watashi ga yonda hon wa omoshirokatta desu.
"The book I read was interesting." — が inside the relative clause; は on the outer topic.
5.3 Assuming 好き takes を
「好き」 (suki, "like") looks like it should take an object, and English speakers instinctively reach for を. Japanese treats 好き as an adjective, so the thing you like is the が-subject of the sentence.
犬が好きです。
Inu ga suki desu.
"I like dogs." — Same pattern for 嫌い (dislike), 上手 (good at), 下手 (bad at), 分かる (understand), できる (can do).
5.4 Using は when nothing has been introduced yet
Openers to conversations — introducing a new person, pointing something out, describing what's happening right now — take が. は is only appropriate once the noun is already on the table.
あそこに男の人がいます。その人は先生です。
Asoko ni otoko no hito ga imasu. Sono hito wa sensei desu.
"There is a man over there. That man is a teacher." — First sentence: が (introducing). Second sentence: は (now known).
5.5 Assuming translation direction is 1:1
English "I" is not always は-私. Sometimes it's が-私 (when you're emphasizing yourself), and sometimes it's dropped entirely because Japanese loves to leave pronouns out when context makes them obvious. The English translation is a hint, not a rule.
6. Quick self-check — five sentences
Pick は or が for each. Tap the answer to see why — no timer, no score, just a quick check that the model above stuck.
1. だれ ＿＿ 来ましたか。 ("Who came?")
Question words always take が. は would mean "as for whom, they came?", which doesn't make sense — you're asking for new information.
2. 田中さん ＿＿ 先生です。 ("Tanaka is a teacher.")
Neutral statement about a known person. Use は to set Tanaka as the topic and comment "teacher" about him.
3. 机の上に本 ＿＿ あります。 ("There is a book on the desk.")
Existence sentences with あります / います take が. The book is being introduced, not framed as a known topic.
4. 私 ＿＿ 犬が好きです。 — wait, actually: 犬 ＿＿ 好きです。 ("I like dogs.")
好き is grammatically an adjective, so the thing you like takes が, not を. The full sentence with the speaker becomes: 私は犬が好きです — topic は + subject が.
5. 私 ＿＿ 読んだ本は面白かったです。 ("The book I read was interesting.")
Inside a relative clause (the part modifying 本), the subject marker が is required. は would break the structure — it can only mark topics at the outer sentence level.
7. Practice more, in context
Reading and hearing dozens of examples in a row is what turns "I know the rule" into "I feel which one is right." The two fastest ways to build that reflex on this site:
- Free particle test — 60 original fill-in-the-blank sentences covering は・が・を・に・で・から and more, with an explanation after every answer. The Leitner box will surface the ones you keep missing.
- Reading comprehension test — short passages at N5 and N4 where you see は and が in real narrative context, not isolated example sentences.