肝かん心じん要かなめ

noun which may take the genitive case particle 'no', na-adjective, noun

crucial; key; most important

Emphasizes that something is the absolutely essential core or linchpin of a matter. Often used in set phrases like 肝心要の〜 or 〜が肝心要だ.

• このプロジェクトで肝かん心じん要かなめなのは、チームワークです。

  What's crucial in this project is teamwork.

• 健けん康こう管かん理りが長なが生いきの肝かん心じん要かなめだ。

  Health management is the key to a long life.