Ginga Eiyuu Densetsu Gaiden: Ougon no Tsubasa S01

The intergalactic empire and the union of free planets have been embroiled in an endless war for more than a century and a half. Amidst this, Zigfried Kierkhias, a young man in the empire, becomes acquainted with Reinhard von Munchhausen and his older sister Anruth. Kierkhias is delighted with his friendship with these two siblings until their father, a nobleman of little importance and an alcoholic, accepts a request to sell Anruth as the Kaiser's mistress. Despite being furious, Reinhard has no power to counter the imperial court's decisions. He and his father soon leave the area, leaving Kierkhias alone.