Set in a universe where men and women are completely segregated (on completely different planets: Mejare by the women, Taraak by the men), the gender wars are more than just a metaphor.

Hibiki Tokai, a third-class laborer, takes up a bet to steal a high-tech humanoid robot, known as a Vanguard, from the male attack force battleship about to fight the "evil females". Caught onboard when it takes off, the battleship is suddenly attacked and all males evacuate, with the exception of Hibiki, Duero McFile, and Bart Garsus. Stuck onboard and held as prisoners with female pirates all around, things seem to have hit an all-time low, until the retreating males retaliate by firing torpedoes at the ship, to prevent it from falling into women's hands. The Paeksys Plagma, the core of the battleship, a mysterious crystalline entity, protects itself by eradicating the missile, while forming a wormhole that sends the pirates and warship to a distant part of the galaxy, and fusing the battleship with the females' pirate vessel. This results in a quirky ship with very smooth lines, a host of technical problems, which some episodes are often aimed at solving, and various hidden capabilities that become apparent in later events. The "Vanguard/Bangaata" Hibiki attempted to steal has also been altered along with three of the women's fighters, known as Dreads, allowing the separate ships to combine. The fusion of Hibiki's mech with one of the fighters is called a Vandread, the title mecha of the series.