かんじんかなめ

肝 心 要

  1. nouns which may take the genitive case particle 'no', adjectival nouns or quasi-adjectives (keiyodoshi), noun (common) (futsuumeishi)

    crucial, key, most important, main (point)

    • そう言えば、肝心要の部分を何も決めていなかった。
      Now that you mention it, I wasn't involved in the decision-making for the vital part.