The boss of the fifth floor of Sword Art Online will drop the Flag of Valor, a dangerously powerful item set to tip the delicate balance between the guilds! Hoping to preserve parity between the two mightiest guilds, Kirito organizes an impromptu raid to be the first to defeat the boss and seize the flag before it falls into the wrong hands...

Nearly two months have passed since Kirito and Asuna found themselves trapped in the world of Aincrad. Now, they're making their way through the ruins-themed fifth floor, where all sorts of undead monsters-and player-killers-lurk in the shadows! The story of Sword Art Online continues in this brand-new series!