She is a guardian, guarding everything about her unknown master. She is just the shadow of the shadow beside her master. She is just an ordinary person, but because of her words "I need a substitute", she becomes a person with super powers in the eyes of others, because she can travel through ancient and modern times. She lives in two time and space, and he and he appear in different time and space...
He is an atheist, and her appearance shakes his world...
He is a theologian, and her appearance makes him doubt his God...
But she abandoned love because of her master...