一ひと山やま越こす

expression, godan verb (-su)

get over the hump; get through the hardest part

Idiomatic expression for passing the most difficult or critical stage of a task or project, after which things become easier.

• このプロジェクトも一ひと山やま越こしたから、あとは楽らくになるだろう。

  We've gotten over the hump with this project, so the rest should be easier.

• 試し験けん勉べん強きょうは一ひと山やま越こしたけど、まだ復ふく習しゅうが残のこっている。

  I've gotten through the bulk of exam prep, but there's still review left.