The Bugle Call: Song of War. Volume 2: Mozuku Sora

A young bugler with supernatural powers is swept up into an epic struggle for the fate of the world. Cry havoc and sound the song of war!
In Arboral Year 1294, the world is dominated by nine massive towers known as the Spires—remnants of an advanced civilization, they are filled with lost secrets and powerful knowledge that nations struggle to possess. Luca is a bugler in a mercenary company who wants nothing more than to leave the battlefield behind and become a true musician, a maestro. But marked as one of the enigmatic Branch-hexed, and gifted with the strange ability to see the sound of his instrument, Luca finds himself drawn reluctantly into a war of epic proportions!
The time has come for Luca’s first real campaign. A fort on the border of the Holy Realm is under siege by the army of the Erin Empire, and it’s up to Luca and his newfound compatriots to defend it. The powers of the Branch-hexed make them unstoppable versus regular troops, but the forces arrayed against them have their own Branch-hexed in service. Luca now faces a true test of his abilities against fierce opposition!