A Mercenary (傭兵, ようへい, "Yōhei") or an assassin is a person who takes up the job of killing anyone in return of payment. They usually do not pledge their fealty to any lords since they are soldiers for hire.
The term has been used particularly for the Band of Seven who are a group of seven notorious mercenaries that travel from the east and take jobs for anyone that would pay. They are well known for their brutal tactics and for killing anyone that is in their way.
- Mercenary on Wikipedia