Verb た-form + が最後

[Once ... (there's no going back)]

Connection: Verb た-form + が最後

Usage: Expresses that once an action occurs, an irreversible or extreme consequence will follow. Carries a strong implication that the result is negative or inescapable. Used to warn or emphasize the finality of an action.

Similar expressions:

• たら最後 = same meaning, slightly less formal

Examples:

あの人は話し始めたが最後、誰にも止められない。(Once that person starts talking, nobody can stop them.)

このゲームを始めたが最後、やめられなくなる。(Once you start this game, you won't be able to stop.)

彼に秘密を話したが最後、全員に知られてしまう。(Once you tell him a secret, everyone will find out.)