Topic は vs subject が: which one to use
Four rules of thumb for choosing は or が.要点The idea
は sets the topic (“as for X…”), while が marks the subject inside the sentence (“X does…”, or “X is the one that…”).Same sentence, one particle changed
A私わたし は 学生がくせい です。watashi wa gakusei desu.I'm a student.As for me: student.
B私わたし が 学生がくせい です。watashi ga gakusei desu.I'm the student.It's me who is the student.
1 · A question word as the subject takes が, and so does the answer
誰だれ が 来きました か？dare ga kimashita ka?Who came?
田中たなかさん が 来きました。tanaka-san ga kimashita.Tanaka came. (It was Tanaka.)
何なに が 一番いちばん 好すき です か？nani ga ichiban suki desu ka?What do you like best?
2 · New information vs something we both know
A庭にわ に 猫ねこ が いる。niwa ni neko ga iru.There's a cat in the garden.New information: a cat has appeared.
B猫ねこ は 庭にわ に いる。neko wa niwa ni iru.The cat is in the garden.Our cat, the one we both know about.
3 · は contrasts
Put は on an object (instead of を), or on a second item, and it can hint at “unlike other things”. Two は in one sentence is almost always a contrast.コーヒー は 飲のむ けど、 お茶ちゃ は 飲のまない。koohii wa nomu kedo, ocha wa nomanai.I drink coffee, but I don't drink tea.
ビール は 飲のみます。biiru wa nomimasu.Beer, I'll drink.…implying: but maybe not the other drinks. Compare the neutral ビールを飲のみます.
4 · Inside the comment, or inside a describing clause, the subject takes が
私わたし は 猫ねこ が 好すき です。watashi wa neko ga suki desu.I like cats.The core sentence is 猫ねこが好すき: “cats are likeable”. は says from whose point of view: as for me.
弟おとうと が 好すき な 歌うたotouto ga suki na utathe song my little brother likesWhen a clause describes a noun, its subject takes が, not は. In short clauses it can also take の: 弟おとうとの好すきな歌うた.
In real conversation
- Aあれ？ 私わたし の プリン が ない。 誰だれ が 食たべた の？are? watashi no purin ga nai. dare ga tabeta no?Huh? My pudding's gone. Who ate it?
- B…ごめん、 私わたし が 食たべた。...gomen, watashi ga tabeta.…Sorry. It was me.
- Aもう！ プリン は 私わたし の 楽たのしみ だった のに…mou! purin wa watashi no tanoshimi datta noni...Oh no! I was looking forward to that pudding…