As I understand it, the copula "だ" turns into "な" in some situations. The most obvious one is after な-adjectives, but it often appears after nouns too, like in this sentence: "スミスさんは、将来日本の会社で働くのが夢なんだって".

Are there any rules for when だ turns into な? It seems to me that if the copula shows up at the end of a sentence it's "だ" and elsewhere it's "な", but I have no idea if it's that simple.


1 Answer 1


when does the copula become "な"?

Simply, だ turns into な when it modifies the following noun, which is の/ん in this case. な is the attributive form of the copula だ. So-called na-adjectives and ordinary nouns are technically both nouns, so they share the similar grammar pattern.

This の/ん is a tiny special noun commonly referred to as explanatory-no. This の/ん is a big topic in Japanese, so please read these first:

So, 夢なのだ/夢なんだ has an added nuance as compared to simple 夢だ. "スミスさんは将来日本の会社で働くのが夢なんだって" may be used in the following situations:

  1. When this sentence works as an explanation/clarification of the previous context.


  2. When this sentence works as a preliminary remark (i.e., background information).


  3. When you just realized this fact.


  • Are you sure that saying "だ turns into な when it modifies the following noun" is correct? The copula だ is still present in the example sentence, but it is now accompanied by な. I'm not sure it's accurate to say that the copula changes into something else. Can you clarify this?
    – kandyman
    Apr 6, 2018 at 11:38
  • @kandyman 夢なのだ is made of four words, 夢 + な + の + だ. This な is a form of だ, too, so there are two copulae. ("It is that it is his dream.")
    – naruto
    Apr 6, 2018 at 13:07

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