Time Gate: Reaper

Death takes on a new form when Uzuki Kasahara, a young teenage girl with a fiery attitude, is entwined within the fates of several individuals, including the mysterious Mitsuhiro Minamimoto, who reveals the truth of Uzuki's existence, which would eventually, but unknowingly, carve its own epic tale in the history of their world.

You can also read the manga adaption here: http://tapastic.com/series/TG-Reaper