Sword Art Online: Calibur

A deity named Urd faces a life-threatening peril, and a group led by Kirito is the only hope for her rescue. Frost giants have attacked her home in Jotunheim, causing widespread devastation. Central to the conflict is a powerful sword, Excalibur, wielded by the leader of the frost giants. The key to restoring peace lies in Kirito and his team reaching the heart of a dungeon and retrieving the sword from a stone. This storyline is drawn from a side arc in Volume 8 of the light novel series.