SuGoiSuす語彙すGrammar › N2 · 01 Conditions and hypotheticals
〜たが最後: once ... (it's the end); once you do
N2 · 01 Conditions and hypotheticals
Says that once a certain thing happens, a bad and unstoppable result follows.
Verb た-form + が最後, then a negative result (usually 〜ない or a bad outcome). Written and a bit dramatic. Example: 借りたが最後、返ってこない. Not used for positive results.
Examples
あの人にお金を貸したが最後、二度と返ってこない。
Once you lend that person money, you will never see it again.
この沼に入ったが最後、抜け出すのは難しい。
Once you step into this swamp, it is hard to get out.