JLPT N1
～が最後/たら最後
once ~ happens, it's all over; if ~ happens, there's no going back
Structure / Usage
Verb (た-form) + が最後 / Verb (たら) + 最後
Example Sentences
あの人は寝たが最後、朝まで絶対に起きない。
Once that person falls asleep, they absolutely won't wake up until morning.
この本を読み始めたら最後、止められなくなる。
Once you start reading this book, you won't be able to stop.