Oversummoned, Overpowered, and Over It! (Manga) Volume 6 by Saitosa

The battle for the Rising Sun reaches its bloody conclusion—and from the ashes will rise only the strongest of souls. Aegiana proves a more dangerous threat than Inori anticipated, and even with all his world-defying power, he’ll need to utilize every tool in his sinister toolbox if he wants to bring his plan to fruition. Meanwhile, deep in the palace, a will stirs, tempered by the flames...

As ideals clash, corridors burn, and walls crumble, dawn finally breaks upon a kingdom in darkness.