Ninja

Throughout history, a ninja was the living embodiment of a weapon. They were hired by rulers to assassinate that rulers enemies. Many believed the ninja used mystical arts and could perform superhuman feats. When a person got assassinated, the ninja would make it look like an accident and go undetected. Being a ninja, they each had their own nickname or title.

In the past, the person had to be literally born into a ninja clan since the ruling dynasty wanted a perfect weapon to carry out a mission without question. So, only a few select villages trained to be ninja. There wasn't often a choice to decline for those villages. The ninja developed a code that they could not live without fighting because they were educated and trained for their entire life to be a ninja and that their only purpose was to be a weapon.