Legend of the Galactic Heroes Gaiden: Golden Wings

Ginga Eiyuu Densetsu Gaiden: Ougon no Tsubasa · 銀河英雄伝説外伝　黄金の翼

Reinhard von Müsel, a poor nobleman's son, one day discovers that his sister, Annerose, has been sold to the royal family. To get her back he sets out to rise quickly through the military along with his friend Siegfried Kircheis. (Source: Anime News Network)