あと まつ
atonomatsuri

Noun
Idiomatic Expression

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

いまさら なげいても、それこそ、後 あと まつりだよ。
imasara nageitemo sorekoso atonomatsuridayo.
You can regret it all you want, but it won't do you any good now.
Other forms: