Niwatori

Niwatori was the Rokugani word for "Chickens".

Ninja
It was also the word Shosuro used with her first year apprentices, members of the Scorpion secret operative. These black-garbed assassins used to carry nageteppo, little egg bombs. During an action a Dragon misheard the word niwatori as "Ninja, tori!" ("Ninja, do what I say!"), and it was assumed the assassins were called "ninja". Since that moment the "ninja" myth was born.