Sword Art Online 28 (light novel) (Volume 28)

Kirito vs. the mysterious gunner Istar! Alice vs. Emperor Agumar! As the battles at the Space Force base and Central Cathedral intensify, a pair of past guardians of the Underworld finally awaken: the vice commander of the Integrity Knights, Fanatio Synthesis Two, as well as one of the Seven Ancient Knights… Meanwhile, back in the real world, Asuna has an unexpected encounter. New beginnings and old reunions await in the seventh volume of the Unital Ring arc!