also: いっぴきオオカミ
noun
lone wolf; loner; self-reliant person
Describes someone who prefers to act independently, often avoiding groups or teamwork. Can carry a slightly rugged or solitary connotation.
彼は一匹狼で、いつも一人で行動している。
He's a lone wolf and always acts alone.
一匹狼の営業マンと
As a self-reliant salesman, he gets results his own way.