This argument has been going on for far too long between my roommate and I and I would very much like some help sorting it out.
A ninja or shinobi was a covert agent or mercenary in feudal Japan who specialized in unorthodox warfare. The functions of the ninja included espionage, sabotage, infiltration, and assassination, and open combat in certain situations. – Wiki
By my reckoning, a ninja is that, and these:
Yagyū Sekishūsai Taira-no-Munetoshi was a samurai in Japan’s Sengoku period famous for mastering the Shinkage-ryū school of combat, and introducing it to the Tokugawa clan.
My roommate would argue however, that these are:
I sort of just want to stick it to him, and end this once and for all. Just because one knows ninjitsu, and assassinates people, that does not make you a ninja.