なくてはならない
(Naku te ha nara nai)
Indicates a necessary action, often felt as a personal or social requirement.
Connection rules
- +Verb (te-form, drop て) + なくてはならない
- +Verb (te-form, drop て) + なくてはいけない
Examples
1.
寝る前に必ず歯を磨かなくてはいけません。

Neru mae ni kanarazu ha wo migaka naku te ha ike mase n.
You must brush your teeth before going to bed.
「Nightly routine」
2.
将来のために、今は一生懸命勉強しなくてはならない。

Shourai no tame ni, ima ha isshoukenmei benkyou shi naku te ha nara nai.
For the sake of the future, I must study hard now.
「Student determination」
Practice
I must do my best to win the match.
試合に勝つために、もっと___。
Romaji also accepted