From Animenfo:
After venturing into outer space, humanity has built many planetary cities. Most of these cities were affiliated with the Interstellar Federation, and it became the biggest force in the galaxy. Therefore, people believed that the Age of the Federation would last long. However, the situation changes when a tribe called “Tytania” secedes from the Federation and receives the title of Lord from the Emperor of Vardhana.
Tytania obtains a victory over the Federation, and they assert that the Empire cannot exist without them. Tytania puts most of the Federal Territories under its control, and they hold hegemony in the galaxy. Meanwhile, a war begins between Euria and Tytania over their respective rights and interests. From that moment on, the galaxy enters into a tempestuous period.