If なくちゃ is followed by another verb, is it read as "you must do X or else Y will happen" or "you must do X and then Y will happen"?

In this sentence (from よだかの星):

Is it: "As for you, it must be a dim cloudy day or night... or else you won't come out."
Or: "As for you, it must be a dim cloudy day or night so that you won't come out."

  • 1
    I'm not sure if you realize, but phonologically (in terms of sound), the ちゃ ending is a contraction of ては, and semantically (in terms of meaning), this ending does not mean "must". The "must" meaning only arises by combining this なくては ending with a similarly negative verb like ならない or いけない. Feb 23, 2018 at 20:59

2 Answers 2


You are thinking of なくちゃ as must, but it's really just a contraction of なくては. なくてはならない and なくてはいけない are used to mean "must", and sometimes the final verb is dropped and なくちゃ by itself is used as a very casual way to imply that something must be done.

However, especially in cases where something comes after the なくちゃ, it can just mean なくては. See Jisho's definition here, and also a related question here.

In short, it's

As for you, it must be a dim cloudy day or night or else you won't come out.

Edit: Also see Eiríkr Útlendi's comment.

  • 1
    I knew it was a contraction, but I didn't know it also had an independant meaning. Thanks for the help.
    – Hyperglyph
    Feb 23, 2018 at 21:09
  • 3
    なくては means "unless". You can simply interpret it as "You won't come out unless it's a dim cloudy day or night" instead of adding a verb and taking it as "must".
    – user4092
    Feb 24, 2018 at 5:30

The existing answers aren't wrong, but I think the question hasn't been fully answered yet.

なくては usually means "without" in a broad sense. Its meaning is actually more neutral than the "unless" translation that user4092 mentioned, and is often a hypothetical condition. Example:


It's important to distinguish also between -ては and -て:

  • 分からなくては心配です "Without understanding (i.e. unless I've understood), it's a worry"
  • 分からなくて心配です "I'm worried about my not understanding"

In the second example, 分からない is an actuality, not just hypothetical like in the first example.

What does the verb after なくちゃ or なくては mean?

More generally, なくては means something like "[something] not being [the case] (at least), what follows will/did occur/is true/is my assertion." This is actually a very broad pattern: gerund + は. See chapter 22B of JSL (which I lifted the above examples from).

You can also follow with an adjectival, or any other predicate: 直さなくては危ないよ!

Even これじゃありません is an instance of this pattern (the gerund being で, where では is contracted to じゃ): this being the case/thing under consideration, it isn't that -> "as for this, it's not" -> "it's not this at least" -> "(it's) not this".

Also, as alternates for "must" there are patterns with と and with the provisional, which are beyond the scope of this question. See What is と in this sentence? and Difference between ~なきゃ and ~なくちゃ

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