The Galactic Empire and the Free Planets Alliance have been locked in a seemingly endless war for more than a century and a half. In the Empire, a young Siegfried Kircheis meets Reinhard von Müsel and his older sister Annerose. Kircheis enjoys a happy friendship with the two beautiful blonde-haired siblings until the day that their alcoholic father, a lesser nobleman with low standing, accepts a request for Annerose to be sold as a concubine to the Kaiser. Although enraged, Reinhard is powerless to stop the whims of the Imperial Court. He and his father soon move away, leaving Kircheis behind.

A few years later, Reinhard returns in a military uniform and declares his intent to rise through the ranks and free his sister from sexual servitude. Kircheis joins Reinhard on this daring journey to save Annerose, yearning to forever stay by the side of his friends.

[Written by MAL Rewrite]

Teppei is going to visit his older brother Kotaro Takamiya during a scientific conference after training with a mysterious woman named Karen for the past 11 years. However his plans for a family reunion become stalled when a woman named Aramis kills everyone in the conference to kidnap Kotaro. Teppei on the way to save his brother encounters a broken mechanical horse called B't X who revives thanks to Teppei's blood and is now his aide to save his brother from the mysterious Machine Empire.

Even as he tries to keep the student council president out of trouble, Vice President Chiga-kun finds himself being drawn to the president's strength and power. Chiga-kun wonders how he, being such an intelligent individual, can be so unwillingly taken with a boy who is so country and simple...

Kozue is a girl who loves astronomy, particularly the stars. One night, on an excursion to witness a meteorite, she meets Ginga, a boy who is able to help scientists discover more information about the stars through a mysterious ability of his. However, he is forced to stay in a protective suit in order to carry out his mission. Because of this, Kozue decides to convince Ginga to make his own decisions & to take off the suit using his own will.