Sword Art Online Progressive, Vol. 5 (manga)

It's time for the 'real' SAO--the third floor! Kirito and Asuna are hardly out the door when they stumble upon the start of the Elf War quest. When they decide to side with the elite dark elf Kizmel, they're set on a path that will push them harder than ever before. But together, nothing can stop them...right?