OK so heres how this works. I'll start the story and you guys have to continue it until we run out of ideas.
So there's this dude who controls everything, even fate.At the beggining of time he created four demon races, and each one controlled one of the four elements. This guy told the demons that they would constantly be at war with each other. He then told them that eventually a demon child named Karu would either save them or destroy them with a single choice. This is the story of Karu.