Sword Art Online 25 (light novel)

Kirito's chance encounter with Eolyne, a man with the same eyes and voice as his
deceased friend, shakes him to the core. But with the possibility of an interworld war
breaking out in the Underworld growing higher by the day, Kirito has no time to be
sentimental. Meanwhile, the decisive battle against Mutasina of the Virtual Research
Society looms, and she's used her powers to force a battalion of one hundred mages
under her command. Can Kirito and company devise a strategy to defy their
overwhelming disadvantage in time, or will it all be for naught?