The Day Before

The Day Before (ザ・デイ・ビフォア) is a side story on Kirito's and Asuna's day after Kirito proposed to Asuna.

Summary
Kirito had just proposed to Asuna the previous day, and she accepted the proposal. Kirito tries to figure out what marriage means for him now as SAO is an MMO game, before actually going through with it. They visit the 22nd Floor looking for a house Kirito had found when the front lines were there, but when they arrive, they find that the house has disappeared.

They try to figure out what happened with the house, and in the process they find the house flying in mid air, with someone trapped inside. They approach the house and find a dog named Toto, which Asuna immediately likes, but Kirito is wary about it. When Asuna tries to pet it, the dog makes them start a quest, and both are sent flying to the house, where they find Argo. Argo explains that she has been trapped for two days in the house because she started the quest but couldn't continue. Kirito and Asuna figure out that the key to continuing the quest was the dog: Toto, and that Argo was afraid of dogs so she ran away from it, entered the house and the event started, but because the dog didn't come with her, she couldn't continue.

Now with Toto with them, the actual quest begins, taking them to an isolated part of the 22nd Floor, where they meet some monsters acting as NPCs and identifying themselves as a lion, a scarecrow and a tin man. They explain that the Witch of the West took their friend, along with their courage, brain, and heart, respectively, and ask them for help. Asuna and Argo immediately figure out that it's a quest based on the Wizard of Oz story, but Kirito doesn't know anything about it, so, despite his doubts, he decides to follow Asuna and Argo.

They arrive at a big castle, where the boss should be, despite Kirito's and Argo's reasons, Asuna brought the dog with them. Taking advantage of their higher level and Argo's agility, they easily arrive at the boss room, where a girl was trapped. An event starts and all of them are paralyzed as part of the event, but also as part of the event they're freed by the lion roaring. Then, they attack the Witch of the West, but not dealing much damage. Asuna lets Toto run free and it makes the Witch fall into the pot, thus defeating her and they then proceed to liberate Dorothy. On their way back Asuna explains the story of the Wizard of Oz to Kirito and he understands that the lion, scarecrow, and tin man had what they needed inside them, and he also had the answer he had been looking for.

Before leaving, Argo gives her thanks to them and promises to keep the secret of their engagement. After Argo leaves with the stealth of a ninja, Asuna starts giggling, thus loosening the tension. Feeling that the last thorn in his chest has disappeared, Kirito navigates his menu and sends a marriage request to Asuna, who then happily presses the "Yes" button.