Legion is the only real faction with a sense of honor, so yeah.
I was leaning more towards Mr House cause he seems more like the type that would hire a Ninja to "clean" but joining the Legion would make sense also.
You could be House's personal Assassin.
That'ld be pretty Boss.
Yea it would.
Oh, and don't forget to wear Stealth Armor/Chinese Suit/ Sneaking Suit MK IV etc. A duster doesn't sound too ninja.
A Japanese Ninja would never wear Chinese armor