Ninjas do not exist. Ninja clans and families disappeared at the beginning of the 20th century, during the Meiji period.
Ninjas were shadows with human form, masters of stealth, infiltration, disguise and many forms of killing, both armed and unarmed. The Imperial State cannot allow the Japanese to have a breed of sinister executioners unless, of course, they also work for the State. The State doesn’t recognize the existence of Ninjas. Rumors about highly skilled assassins that execute the darkest missions of the State are just that: rumors. A Ninja has never been caught alive…
