Sword Art Online, (Light Novel) Vol. 16

Gabriel Miller-assuming the identity of Emperor Vecta, the god of darkness-prepares to invade the human lands with his army of fifty thousand. Defending these lands are the remaining Integrity Knights, led by Commander Bercouli, and an army one-tenth the size of the enemy's! Meanwhile, Kirito, still out of commission, is left in the care of primary trainees Ronie and Tiese. And back in the Dark Territory, Dee Eye Ell, the chancellor of the dark mages guild, threatens to vanquish the Human Guardian Army by launching a large-scale magical attack of her own. But in the midst of the chaos, the one who appears to turn the tide of battle is none other than...Asuna?!