Board Thread:Theories and Speculation/@comment-27295021-20180308012211/@comment-4974066-20180308014746

I dont think there is anything keeping anyone (samurai or not) from becoming a shinobi other than the willingness to do so. The series seems to put forth this idea that samurai are a dying breed with the Land of Iron being the only country that employs them. There have been samurai outside the Land of Iron that take part in the shinobi world such as Zori and Waraji, but we dont know their backstories or why they choose to do that (or atleast, I dont remember lol). If I recall, Hanzo says that alot of samurai became shinobi and samurai schools began teaching ninjutsu, so your example seems to be pretty much what happened to alot of samurai anyways. It should also be noted that since the 4th Ninja war where the Land of Iron also got involved, relations between the samurai and shinobi seemed to have opened up more. But whether that means there will be more or less samurai in the future is unknown.