Translation guide
A hidden advantage or resource kept secret until needed.
To express that someone has a secret plan, skill, or resource that will give them an advantage when revealed.
Literally 'trump card'. This is the most direct and common equivalent for 'ace up one's sleeve', referring to a decisive hidden resource or strategy.
彼はまだ切り札を隠している。
He still has an ace up his sleeve.
交渉の最後に切り札を出した。
He played his ace up his sleeve at the end of the negotiation.
Literally 'hidden hand/technique'. Implies a secret move or last resort, often used in competitive contexts like sports or games.
Literally 'hidden ball/piece'. Used for a secret weapon or surprise element, often in sports, business, or entertainment.
彼は奥の手を使うタイミングを待っていた。
He was waiting for the right moment to use his ace up his sleeve.
新製品が我が社の隠し玉だ。
The new product is our ace up our sleeve.