Here is the initial variant of dialogue:

A: 誕生日はいつですか。
B: 5月19日です。
A: 5月ですか。私の誕生日も5月です。同じですね。

In this context it would be more native to say "私も5月です". But the question is specifically about "私の": Is it okay to omit the "私の" here from a theoretical point of view? From a practical point of view, can native speakers omit it?

Is this variant still possible to any extent:

A: 誕生日はいつですか。
B: 5月19日です。
A: 5月ですか。誕生日も5月です。同じですね。

I've read that if a pronoun is omitted from a sentence, the default is to always assume 私 unless the context makes it clear that it's someone else. Does this rule also apply in this example?

3 Answers 3


No, it's not OK.

When you say 誕生日も, you are putting 誕生日 in the same category as something else. In this case it is another 誕生日 that has been just mentioned. You need to be specific about whose 誕生日 it is.

You can say 私も五月です to put 私 in the same category as あなた. This sounds completely natural.

  • Simple and to the point.
    – istrasci
    Commented Feb 5 at 16:59

You've already established the context (and the topic) by asking the question:


You're talking about the individual who you are conversing with.

I think you would be understood if you said,


but there would be some head-scratching: who else also has a birthday in May?

The degree to which this statement would be properly understood is going to be highly contextually dependent.

For example if you'd just been talking about your mom right before asking, "when's your birthday?" They'd probably still scratch their head but decide it must be your mom who also shares a birthday in the month of May.

Essentially you're shifting the topic of conversation from discussing details about the person standing in front of you (or on the other end of the phone call etc). The question then is who/what did you shift the topic to?

They might even ask,


It is not uncommon in Japanese to hear folks say things like だれが or 何を. (My sense is that they occur with greater frequency than these questions do in English, but that's not surprising given the highly context dependent nature of Japanese.) Neverthelss, I think, if you're going to be dramatically shifting the topic (from A to B), then it's good to make clear what the new topic is. These sorts of questions of だれが or 何を, while they crop up even amongst native Japanese, they usually crop up in contexts where a variety of topics are being discussed and something unexpected sounding crops up.

As you pointed out, when there is no established topic, the topic can default to 私. But, once another topic has been established, you should probably re-introduce yourself as the topic by saying 私も/は. And 私の would also make clear who you're talking about.

The question was raised in the comments about the naturalness of 5月ですか. I'm a bit on the fence about this. I'm not a native speaker and hesitate to opine on things that tread a bit into intuition. But I'll nevertheless stick my neck out.

My sense is that it would certainly be understood as a rhetorical question. I'm not sure exactly how a native speaker would raise a similar echoing what the speaker just said.

But this matter perhaps is delving too much into the weeds here when the primary question was about when you can assume "I" remains the unspoken topic.

  • +1: Could you say something about the naturalness of 5月ですか? It feels weird to me but I don't have the confidence to comment. Commented Feb 4 at 18:00
  • @user3856370 Good point. I'll think about that.
    – A.Ellett
    Commented Feb 4 at 18:02
  • @user3856370 - I'm curious why you think it's weird.
    – aguijonazo
    Commented Feb 4 at 19:54
  • 1
    同じですよね sounds weird here. It would sound like the other person already knew they were born in the same month and the speaker is confirming that knowledge.
    – aguijonazo
    Commented Feb 4 at 19:58
  • 1
    @user3856370 - I wouldn't stop to think about its naturalness. It could've been そうですか, of course, but the speaker had a reason to specifically point to the fact that it is May. There is a little bit of surprise here.
    – aguijonazo
    Commented Feb 4 at 20:16

I've read that if a pronoun is omitted from a sentence, the default is to always assume 私 unless the context makes it clear that it's someone else. Does this rule also apply in this example?

No, because simply saying 誕生日も doesn't entail that a pronoun is being omitted. It's perfectly legitimate to talk about birthdays in general, rather than about a specific person's birthday. 私 might be in some sense a "default" answer to the question "whose"?, but that only applies if the question is actually raised.

But the question is specifically about "私の"

No. The question is specifically about "Bの", because A asked it.

Imagine a hypothetical "high-context English" exchange:

A: When is the [your] birthday?

B: It [[my] birthday] is May 19.

A: [[[Your] birthday] specifically is in] May? My birthday, as well, [is in] May. [[My] birth month] is the same [as yours], eh?

In this language, we would not expect A to be able to drop the un-bracketed "My", because it pertains to a different birthday than any that was previously mentioned. It can't be inferred from context because it is not actually contained in the context from which it might be inferred.

But A could drop the un-bracketed "birthday". In fact, English speakers do that all the time, even though English-speaking cultures are usually much lower-context than the dominant culture of Japan. In English, "Mine's in May too" sounds perfectly natural. We might even just say "Me, too", if the previous sentence gives enough context. (This "me" is, in my analysis, a form of topicalization - rare in English, more common in French I think.)

Analogously in Japanese, we could have 私も5月です as aguijonazo describes: "Also for me (the part that isn't in the context and needs to be contrasted), it's (referring to "one's birthday", as a general concept, deduced from context) in May."

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