Japatan
Formation
- Vた形 + ら + 最後
- Vた形 + が + 最後
Explanation
A たら最後 B / A たが最後 B means 'once A happens, there is no stopping it and B will surely follow.' B is an irreversible or troublesome result, such as 'won't stop' or 'can't ~.' It is often used for someone's habits or for rules. たが最後 is slightly more formal.
Examples
兄はゲームを始めたら最後、呼んでも返事をしない。
Once my brother starts playing a game, he won't answer even when you call him.
部長は話し始めたが最後、一時間は終わらない。
Once the manager starts talking, he goes on for at least an hour.
この店のパンを一度食べたら最後、ほかの店のパンでは満足できなくなる。
Once you eat this bakery's bread, you'll never be satisfied with bread from other shops.
期限を過ぎたら最後、申し込みは受け付けてもらえない。
Once the deadline passes, your application will not be accepted.
Notes
It is not used as a simple 'when/after' or for good results and plans. With verbs whose ta-form ends in だ, it becomes 読んだら最後, 飲んだが最後, etc.
Mini quiz
1父はソファーで寝てしまっ（ ）、朝まで起きない。
Answer and explanation
Answer: 2 たら最後
"Once my father falls asleep on the sofa, he doesn't wake up until morning." たとたん (the moment, past events), たばかりに (just because) and たところ (when I did ~) do not fit.
2この書類は一度提出し（ ）、もう直すことはできない。
Answer and explanation
Answer: 4 たが最後
"Once you submit this document, you can no longer correct it." たあげく and たすえに (after a long process) and たついでに (while doing ~) do not fit.
3「たら最後・たが最後」の使い方がいちばん正しい文はどれですか。
Answer and explanation
Answer: 1 一度約束を破ったが最後、もう信用してもらえないだろう。
1 means "Once you break a promise, people will probably never trust you again." 2 is a plan, 3 is a past discovery, and 4 is a pleasant result, so they are wrong.
