This post on the official Google blog got me thinking: we have the Pittsburgh Pirates; why isn't there a team called the Ninjas? (Don't even get me started about the Robots and the Zombies, OK?)
For alliterative advantage, the home city should also start with an N - Nagoya comes to mind. Unfortunately, it seems that the whole ninja fascination is more of an American thing, and there are no Japanese teams called the Ninjas. But imagine the possibilities!
(Nagoya has a minor-league team called the Dragons. Somebody should whisper in their ear, don'tcha think?)