User blog comment:AssassinRome/Assassins in Japan?/@comment-3058930-20120805212727/@comment-1153722-20120807120201

Hattori Hanzo was a loyal servant of Tokugawa Ieyasu, and a samurai trained in shinobi arts. That would just put more to the "Assassins are ninja!"-fire. They could instead make him an Assassin instead of a ninja though.