The story unfolds in a faraway place... the Gurhal System. The three planets that make up the Gurhal System are populated by humans and three other races born of the humans--Newmans, Beasts and CASTs. Wars between the races raged for 500 years, but the races eventually settled into a moderately peaceful coexistence. But now, after a century of peace, certain devastation arrives ... Seventeen-year-old Ethan Waber and his sister Lumia were attending the grand ceremony commemorating the centennial of the Gurhal System's Tripartite Treaty when suddenly a mysterious alien species known as the SEED launched a surprise attack. The Alliance Military's armada was completely unprepared for the sudden invasion and was all but destroyed as the ceremony's attendees succumbed to panic. In the ensuing chaos, Lumia is left behind in the rubble.  In order to save his little sister, Ethan borrows some equipment from a Guardian named Leo, and for the first time in his life, he's flung into a dangerous battle of life and death...