Sword Arts Online Season 2 Episode 15 is about the group traveling back to Alfheim. This chapter is now available online in sites like animefreak.tv and crunchyroll.com. Season two returns with a new episode and new season arc Kirito and Asuna who are off on a new adventure for the legendary special sword Excalibur.

The episode started with Kirito and Suguha having breakfast where Suguha reminded is brother of their prior quest to Alfheim. According to Anime News Network, the bizarre flashback revealed that Kirito and Suguha were once swallowed by a giant worm that brought them out in an icy Alfheim underworld. There, they saw a four-armed giant bullying an elephant-jellyfish, which Suguha demanded Kirito to rescue. Sugu named the saved creature Tonkii. It grew wings and flew them to the surface.

Suguha then shares about a recent discovery of an Excalibur sword within the game to Kirito. He called Asuna and asked her to join them in search for the Excalibur. Kirito also asked Sinon to come with them. Sinon is now sporting a cat-type avatar for the MMO in Alfheim and has retained some elements of sniping, as she uses a bow and arrow in this game. According to ganbareanime.com, Sinon has "jumped from GGO to ALO out of nowhere, and it feels as if she's always been a part of their group."

The group sets out to the icy and snowy underworld of Alfheim. They ride Sugu's animal friend and meet an AI that asks them to steal Excalibur from a demon race that is trying to turn the World Tree area into the same ice and snow environment of the underworld.

After resolving all of the conflicts, Kirito can actually play a game completing quests and having fun with his friends.

Asuna revealed that she'd be leaving back to Kyoto soon.