Claus Valca is from the world of Prester where he and his longtime friend, Lavie live and work as sky couriers. They pilot a van-ship left to Claus by his father. Together they dream of one day making the journey their father\'s were never able to complete - flying acros the notoriously dangerous stretch of space known as the \"Grand Stream.\" One day, after Claus and Lavie agree to shuttle a mysterious girl named Alvis Hamilton to the air-battleship, Silvana, they become involved in a war that...

The year is T.C. 4767. Four thousand years have passed since humanity abandoned its birthplace, the planet Earth. Beset by the hostile alien Gnosis, mankind is now scrambling to find ways to defeat this threat to their existence. The development of KOS-MOS (a specialized android with amazing capabilities) by Vector engineer Shion Uzuki was one response to the threat. But when their ship is destroyed by the Gnosis, Shion and her companions find themselves thrust into the middle of a battle with...