In 2026, a new augmented-reality device called the Augma becomes immensely popular thanks to Ordinal Scale, a game that turns the real world into an adventure. Kirito joins Asuna and their friends when they discover that former Aincrad bosses are appearing in the game. But behind the battles and performances of the virtual singer Yuna, strange incidents begin affecting survivors of Sword Art Online. When Asuna starts losing her memories of Aincrad, Kirito sets out to uncover what Ordinal Scale is really hiding. His investigation brings him into conflict with a mysterious player and a project that could endanger everyone who survived the deadly game.