I'm a Girl from the Future

Can a person's life really be a calm, undisturbed sea? Or does it take just one little stone to send the whole surface into a raging storm?

Everything changed when that mysterious girl transferred into my school.

With her hands behind her back and an enigmatic smile, she came closer. At first, I didn't think much of it. But then she leaned close to my ear and whispered:

"I am you, from the future."

(Just a wild idea, nothing more.)