...The Ninja were basically rural types who had to think outside the
bushido box, and therefore got a reputation for deception and trickery; the legends of mystical powers came later. It's like assigning magical powers to The Beverly Hillbilliesnote and then having them topple governments and hire out to the highest bidding supervillain. Okay, my version of The Beverly Hillbillies movie probably would have sucked, too, but it wouldn't have been dull
Did you hear that? Woman:
Because it's a ninja. Run.
We feel the fire burning bright in the night,
Where the warrior lives, and the warrior dies!
Wherever you go, we will be by your side,
For the spirit of Ninja will carry the night!
He is stronger than steel and moves faster than a whirlwind.
Sometimes he hides in mud. Other times he transforms his shape like an ever-changing cloud.
Although his fighting spirit burns like fire, his mind is as calm as still water.
"Violation of the Commandments"
Should shinobi fail before completing the mission, he will disappear before the dawn and vanish forever.
Keep this knowledge in your heart and mind.
— Excerpt from the Secret Manual of Oboro Ninjutsu, quoted in the intro of Shinobi III: Return of the Ninja Master