一ひとつ穴あな

noun

same hole; living in the same den

Literally 'one hole'; used figuratively for people who share the same living space or are in the same boat, often with a negative or conspiratorial nuance.

• 彼かれらは一ひとつ穴あなのむじなだ。

  They are birds of a feather (literally, badgers of the same hole).

noun

gang; group; coterie

Often used in the set phrase 一つ穴のむじな (badgers of the same hole) to mean a group of people with shared, often shady, interests.

• あの連れん中ちゅうはみんな一ひとつ穴あなのむじなさ。

  Those guys are all in the same gang.