It's reported that the Holy Sword Excalibur has been discovered inside ALO. Several months earlier, Kirito and Leafa had found this sword in Jotunheim, an underground realm, where they had saved a beast-type god named Tonky. Hearing the news, the siblings make up their minds to take possession of Excalibur before other players get to it first. Summoning Asuna, Klein, Sinon and the others, they set off for the dungeon in Jotunheim as a 7-member party.