Based on a science fiction novel series, Crest of the Stars (Seikai no Monsho) is the first installment in this sci-fi saga. The story follows Jinto, whose world was taken over by the largest empire in the galaxy: the Abh. Jinto's father, the planet's prime minister, handed their world over to the Abh in exchange for a standing in the Abh Empire. As a result, Jinto became a prince and was shipped off for an Abh Education. There he meets a princess of the Abh Empire, Lafiel, whom he quickly befriends despite her cold exterior. The Abh Empire is plunged into war soon after and the story continues from there...

Three years after their adventure, Lafiel becomes captain on the brand new assault ship Basroil and Jinto finishes his training to become a supply officer and joins Lafiels crew. They set out to join a large fleet with the mission of defending the strategically important Laptic Gate from a force 15 times larger than their own. And to bring even more worries, their new fleet commander is from the Bebous family, a family notorious for their "Spectacular Insanity".

Due to a lack of ambassadors for the recently-conquered worlds the rapidly advancing fleet of the Bebaus brothers leave behind, Lafiel is appointed Territorial Ambassador of the planet Lobnas II. Upon arriving to the planet Jinto and Lafiel discover that the planet was used by the United Mankind as a prison planet and now has a million prisoners on the only inhabited island. The prisoners are parted in three blocks. The western where women are housed, the eastern belongs to the men and the central is mixed under the restriction that all prisoners living there are sterilized. The women in the western sector want to emigrate from the planet of fear for the men and when they do the men in the east rebel, overthrowing the guards and capturing Jinto to try to stop the emigration of the women. At the same time an enemy fleet heads toward the system forcing Lafiel to abandon Jinto.