neko-chan wrote...
Of those three, the final idea is the only one that does not seem cliche.
Perhaps a bit of advice is to change the order in which you are writing this story. Start with an antagonist first. Think about him or her: who are they? what is their past? Is the antagonist a person or an entity of some sort? Why are they evil? Are they pure evil or are they just self-righteous?
When you answer those questions, you can answer a final question about them: What are they trying to accomplish? Once you answer that question, you have your answer for why the hero must stop whatever it is you want them to stop.
i agree, cause there is more story in the third idea. is the ninja girl going to be the only one going to be the only protagonist? :U