黒幕

mastermind, power behind the scenes

k ɯ̟ ɾ o̞ m a̠ k ɯ̟
black + curtain
noun Rare #32,983
mastermind, power behind the scenes Usually refers to someone secretly controlling events or influencing decisions from behind the scenes, often with a negative implication.
JA: 事件の黒幕はまだ分かっていない。
EN: The mastermind behind the incident has not been identified yet.

私は誰が黒幕か知っている

I know who the mastermind is.

彼らがその陰謀黒幕であった

They were the masterminds behind the conspiracy.

黒幕的な存在は誰だ

Who is the mastermind behind it all?

この事件の陰に誰か黒幕がいるに違いない

There must be someone pulling the strings behind this incident.

お互いキャリアにとって誰が黒幕なのか言ってた

Did you say who the mastermind behind both of their careers was?

— 善き人のためのソナタ (2006)