noun
black curtain
Literal meaning: a black curtain used in theater or as a backdrop. Less common in everyday speech than the figurative sense.
舞台の黒幕が静かに上がった。
The black curtain on the stage rose quietly.
noun
wirepuller; mastermind; éminence grise
Figurative use: a person who controls events from behind the scenes, often in politics, business, or crime. Carries a slightly negative or conspiratorial tone.
事件の黒幕はまだ捕まっていない。
The mastermind behind the incident has not been caught yet.
彼は政界の黒幕として知られている。
He is known as a power broker in political circles.