[quote=@Ves]
Your character's 'Ninja Way', I assume. Their motto, belief, and such.
[/quote]

[@Raineh Daze]

That exactly. 
Naruto vows never to go back on his word (a nindo adopted by others, like Gaara and Hinata). 
Obito/Tobi once said the an Uchiha's nindo is to exact revenge against those they hate. 
Lee and Guy follow their 'My Rules' philosophy thing. 
The Senju insisted that the Will of Fire is a Universal nindo for all shinobi.
Iwagakure ninja have their Will of Stone, suggesting that a ninja should be strong willed. 

Not everyone necessarily has one. If you find that something doesn't apply, feel free to skip it.