Voices of a Distant Star (2002)

The story of the high school students Mikako Nagamine and Noboru Terao. When the alien Tarsians attack, Mikako volunteers to be a pilot in the space force that will protect mankind. The lovers try to remain in contact using cellular telephone text messages, but as each battle takes Mikako further from the Earth, each message takes longer to arrive. Will their love stand the tests of time and distance?