Seikai no Senki Series by Hiroyuki Morioka

Lafier has been appointed the interim liege of yet another newly conquered star system, with Jint her ill-defined adjunct... moreLafier has been appointed the interim liege of yet another newly conquered star system, with Jint her ill-defined adjunct. Only the planet of Rohbnahss is by far the most vexing of the Empire’s latest acquisitions—because it’s a giant prison on the verge of a world-scale uprising! Can the iconic duo form a working government there? What will become of them and their bond once the enemy’s offensive and her Abliar obligations force Lafier to abandon Jint on a powderkeg ready to blow? Find out in this, the second exciting installment of Banner of the Stars! less

Lafier is now the captain of a state-of-the-art raid ship, and her brother, Duhier (who is still wrestling with his inferiority complex) has finally enlisted in the Star Forces. Meanwhile, the galactic war is reaching a turning point, as the Hania Federation asks to join the Abh Empire. Will the Empress accept their offer? And might Hania have ulterior motives?

The unthinkable has happened: the imperial capital is under siege by the Three Nations Alliance thanks to a surprise attack, which will divide the Empire in two. The Empress and the Empire’s paltry forces at the scene must rally in a bid to evacuate what people and structures they can, and buy time for the capital’s relocation. Lafier and Jint are charged with saving the Empire’s culturally significant artifacts, even while Lafier’s brother Duhier is stranded behind enemy lines.