The song eX Dream by Myuji (which appears in an anime OP) contains the sentence:


The general point of the sentence is fairly clear, meaning "a dream is just a dream". But what is the best way to think of the でしかない construction?

At first I saw it as 夢は夢で, as in, "a dream is a dream and...", but now I'm wondering how correct this is or if it's correct at all.

Is it better to look at it as a separation of the parts of である? Does this happen in many other cases, where you use a qualified で followed by ある?

2 Answers 2


Let's start with something common:

夢は夢だ。 'Dreams are dreams.'

Let's negate it (using ではない instead of its contracted form じゃない):

夢は夢ではない。 'Dreams are not dreams.'

は is a 係助詞{かかりじょし} ("binding particle"). Any 係助詞 fits in this spot. しか is also a 係助詞:

夢は夢でしかない。'Dreams are nothing but dreams.'

The "modern" grammatical analysis of this stuff is that で is the 連用形{れんようけい} ("continuative form") of the copula だ which results in ではない and でしかない falling nicely into this general rule:

(連用形 of something) + (optional 係助詞) + (ない or ある)

Some other instances of this rule are すごく(は)ないあつく(も)ないバカで(も)ある

  • 4 years later, I'm quite interested about the last part. I recently read about 悪くはない vs 悪くない, and while I understand the difference in nuance, I'd like to understand the underlying grammar. I might be wrong by thinking that は is supposed to modify nouns only, so 悪くは〜、すごくは〜 sounds really really weird to me. Perhaps if you have some more reading material about the rules related to it or perhaps there is some historical/etymological reason to it, could you please provide me with some links? Much thanks!
    – xTCx
    Aug 19, 2017 at 16:55

If you were to say 夢は夢しかない then it would have a meaning of something like "dreams have nothing but dreams." It's the simple ~は~が construction you learn in Japanese 101 to describe a particular feature of a subject. This is not a copula.

As you mention, you should be looking at it in terms of である. If you take out the しか you'll have the normal copula 夢は夢ではない, which you will recognize is that full form of "じゃない." So this way of sandwiching しか into it allows you to get the "only" meaning of しか while preserving the copula である.

As for other cases, I"m not sure if you mean other cases of でしか or other words with である. For でしかない you can expect to see it wherever the meaning is appropriate as it's not a particularly exotic expression. For other combinations, you can compare it to でもある, which is how you say that something is also something else (その人は研究者です。先生でもある。).

  • Ah I see, I had heard the でもある in passing before without recognizing it fully. This is what I was looking for.
    – AlanSE
    Aug 26, 2013 at 23:59
  • For the record I fully endorse the other one being the selected answer
    – ssb
    Aug 28, 2013 at 10:32

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