陰かげで

expression

behind one's back; in secret; covertly

Used when someone does something without the knowledge of the person concerned, often with a negative connotation.

• 彼かれは陰かげで悪わる口ぐちを言いう。

  He speaks ill of others behind their backs.

• 陰かげでこそこそするのはやめてください。

  Please stop doing things secretly behind people's backs.