こなければ

if (someone) doesn’t come, unless (someone) comes, must come

→ 来る

こ come; arrive + なけれ Negative conditional + ば Conditional (“if”)

auxiliary · informal Rare #45,654

if (someone) doesn’t come, unless (someone) comes Often used with ならない to mean “must come.”

JA: 今日こなければ、あとで連絡してください。

EN: If you don’t come today, please contact me later.

must come Used in the expression こなければならない.

JA: 明日は早くこなければならない。

EN: I have to come early tomorrow.

Conjugation of 来る

Conditional

きたらくればこなければ

If I hadn't come back here...

— レベッカ (1940)

I wish I'd never been born.

It would have been better if you had never been born!