Her Majesty's Swarm: Volume 4

After subjugating three countries, Grevillea sets her sights on her next target: the supreme military power and land of swooping wyverns, the Nyrnal Empire. In order to secure a path into the country, she must first seize the neighboring Eastern Trade Union. The Union’s capital city of Khalkha is a paradise where any and all pleasures are within arm’s reach—but when Grevillea and Emperor Maximilian vie for supremacy, will its utopian streets run red with blood? The Arachnea and the Empire, the two remaining great powers on the continent, clash for the right to rule. As Grevillea’s secrets are dragged out into the light, the story hurtles toward its climax!

[From J-Novel Club]