後の祭り

Meaning

1. expn
   a day after the fair; (at a) stage when it's too late

Example sentences

• 今更悔やんでも後の祭りだ。

  It is too late to repent.

• 今となっては後の祭りだったが、彼はどうして自分達が試合に負けたのかよくわかった。

  With 20/20 hindsight, he could tell why they lost the game.

• 今さら騒いでもどうにもならないよ。後の祭りだよ。

  Yelling about it won't help now. You should have done that when it counted.