The Iga ninjas rose in mutiny on 1579...
You are a samurai. You think of the ninja on your side because you don't know ninjas' mutiny. You can't attack him. All you can is avoid his attack.
The ninja is an enemy. He used to be on your side, but now he is not. He attacks you with various weapons and himself. He uses various ninja arts.
Touch and swipe the screen with your finger. The samurai follows it.