- This page is about the whole Calibur story. You may be looking for the Calibur quest, the Excalibur sword, the novel story, manga adaption or the alternative Calibur SS non-canon side story.
On December 28, 2025; Kirigaya Suguha (Leafa) showed her cousin, Kirigaya Kazuto (Kirito), a news article, stating that the Holy Sword Excalibur in ALfheim Online (ALO) had been found. Excalibur was the rarest and most powerful sword in ALO, but the two siblings were unable to defeat the guardians of the dungeon that the sword was held in, despite having known the location of the sword for a year. Thus, they temporarily forgot about the sword due to more important matters. However, Kazuto was then told that the weapon had only been discovered so far, but not yet acquired. Thus Kazuto called Asuna, Lisbeth, Silica, Klein and Sinon to form a full party and attempt to clear the dungeon again. However, after they arrived at Jötunheimr and got on Tonkii's back, they discovered that the other players discovered the location of the item via a quest that required slaughtering the beast-type Evil Gods. The group was then approached by an NPC named Urðr, who informed them that the slaughter was requested by the king of the frost giant tribe, Thrym, who had promised Excalibur as the reward for the help. However, unbeknownst to players, he needed to massacre the beasts in order to break Urðr's protection that prevented him from invading the land of the fairies, Alfheim, and causing a cataclysmic event known as Ragnarok. Urðr then requested for the fairies to retrieve Excalibur from the bottom of Thrym castle, Thrymheim, before the last beast-type Evil God was killed, as once the sword was removed, Yggdrasil would be able to grow its roots back into the Great Void, restoring its blessings to the world and causing Thrymheim to melt.