肝かん心じん

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

essential; crucial; vital; key

Describes the most important or indispensable part of something. Often used in set phrases like 肝心なこと (the crucial thing) or 肝心な時に (at the critical moment).

• 肝かん心じんなのは、最さい後ごまであきらめないことだ。

  The essential thing is not to give up until the end.

• 肝かん心じんな時ときに限かぎって、彼かれはいない。

  He's never around at the crucial moment.