Armed with a large sniper rifle, Hecate II, the young girl Sinon is making a name for herself as the No. 1 sniper in GGO. When her squadron ambushes another squadron, she succeeds in taking out her first target. But when she takes aim at her second target, a robed “Behemoth,” he dodges the bullet.

Kirito and the others are tasked with subjugating the Frost King Thrymr, and a quest to recover Excalibur. It's Yui's guess that this isn't a quest planned by the game admins, but something automatically generated by the system. And if that's the case…