Seikai no Monshou

After his home world is ruthlessly taken over by the Abh - a space-faring race that has conquered thousands of galaxies - a boy named Jinto begins an unforgettable journey that stretches the boundaries of the final frontier. With a beautiful princess at his side, he will attempt to unlock the secret behind the Abh domination and discover that all's fair in love and interplanetary war.

(Source: Tokyopop)

Seikai no Monshou was published in English as Seikai Trilogy by Tokyopop from June 8 to October 12, 2004. The volumes are unnumbered, but subtitled Crest of the Stars, Banner Of The Stars I and Banner Of The Stars II