Sword Art Online: Hollow Realization Vol. 6 (manga)

Despite everyone's best attempts, the Great Separation and resurrection of Aincrad have begun to dismantle the world of SAO. Now Kirito and his friends must head straight into the heart of the floating castle and stop Premiere's other half, Tia, but can they make it in time to save their beloved game?! Stakes are high in this final showdown of Hollow Realization!