Returner (2002)

Director: Takashi Yamazaki
A young woman from the future forces a local gunman to help her stop an impending alien invasion which will wipe out the human race.
After an alien invasion threatens to annihilate the human race, a young Japanese girl, named Milly, travels back in time from 2084 to October 2002, and enlists the reluctant aid of skilled Tokyo gunman, named Miyamoto, to discover and prevent the start of the war.