"I accept the power of your existence."
After accidentally traveling through time, this is actually a different world that is about to be ruled by alien "spirits".
And their method of ruling the world is to devour the existence of life. What's even more terrible is that if the existence of this world disappears, then there will be no original world.
It tells various life-threatening stories about a useless boy and a girl who inspires to become the world's number one "Guardian".