一人じゃ

alone

→ 1人

phrase Common #3,682

alone A contraction of 一人では, often used before a phrase meaning that something cannot or should not be done alone.

JA: 一人じゃできない。

EN: I can't do it alone.

By myself...

— レミーのおいしいレストラン (2007)

You probably shouldn’t go alone.

Besides, you can't handle it alone... Your opponent is a sick old man.

— サイコ (1960)

I'm not alone.

— 続・夕陽のガンマン (1966)