also: やみよにからす
expression, noun
something indistinct; hard to tell apart
Idiomatic expression literally meaning 'a crow in a pitch-black night', used to describe things that are difficult to distinguish or recognize due to darkness or similarity.
See also: 闇夜に烏
闇夜の烏で、どちらが本物か見分けがつかない。
It's like a crow in the dark night; I can't tell which one is the real thing.
この二つの書類は闇夜の烏だ。
These two documents are as indistinguishable as a crow in the dark.
Variant form with the same meaning; 闇夜の烏 is more common.
A classical Japanese idiom; the exact origin is uncertain, but it draws on the image of a black crow being invisible in the darkness of night, symbolizing indistinguishability.