んじゃ => If ... then... N4
Condition (hypothetical condition)
ないと/なくちゃ/なきゃ => must do; need to; gotta do ~ N3
~あるまじき => ~ Unacceptable, not allowed N1
Ban
じゃないが => It's not that... but... N4
How to say the beginning
じゃ(あ) / では => Then, so (Expressing attitude) N5
Change the way you speak
んじゃない => can not, impossible to... N4
Ban
~じゃ(では)あるまいし => isn't it; I wonder if it's not ~ N1
Invite and advise
じゃないか => right? isn't it? let's~; confirmation N4
Speculation
じゃありません => not to be N5
Emphasize negative meaning
じゃ(あ) / では => then; well; so; well then N5
Change the way you speak
んじゃなかったか => shouldn't have... N4
Regret
~まじき      => should not; must not N1