On December 2, 2022, Kirito reflected on how more than 2,000 players had died since the start of the Sword Art Online official service a month ago, while the 1st Floor had yet to be cleared. Even Kirito, a former beta tester, had been unable to locate the boss room. A meeting was being held in Tolbana to discuss how to find and defeat the 1st Floor Boss.
A self-proclaimed knight, Diavel, called the meeting to order at the town center of Tolbana. After a brief moment of joking among the attendees over the lack of a job system in the game, Diavel regained their attention and announced that his party had located the boss room at the top of the Labyrinth, much to their surprise. He declared that they, as the current strongest players of the game, had a duty to defeat the boss and reach the 2nd Floor, as well as inform the other players in the Town of Beginnings that it was possible to clear the game, and his proclamation was received with enthusiastic approval. Diavel suggested the players to form parties with each other, as a raid group would stand a better chance against the boss than a typical party. As Kirito panicked when he saw that practically everyone else had already formed parties, he noticed a hooded girl alone and asked her to form a party with him, which she accepted. After forming the party, Kirito noticed her name, Asuna, beside her hit point gauge.
After the parties had been formed, the meeting was interrupted by a player who introduced himself as Kibaou. When he demanded an apology from several vague players for the 2,000 deaths in the game, Diavel realized he was referring to the former beta testers. Kibaou affirmed the notion and accused the beta testers of not offering any help to the beginners and instead seizing all the best hunting grounds and easy quests for themselves. He then stated his suspicion that there were beta testers in the meeting and that they should relinquish all of their items and money, otherwise they would not be trusted by the others. However, Agil intervened and defended the Beta Testers, stating that they should not be fully blamed for the tragedies of the fallen players as they had already helped by distributing their knowledge of the game through a manual and that everyone had equal access to the information, and Diavel and the rest of the attending players were revealed to have a copy of the book. After the commotion ended, Diavel read the information book to the players in the crowd, telling them that the boss on the floor was Illfang the Kobold Lord, and that he had minions, called Ruin Kobold Sentinels. He also told them on his last bar of HP, the boss would discard his weapons and equip a Talwar and use a different combat style. Thinking that the book was completely correct, the attending members decided not to scout the boss to check if there was any mistake on the book and planned to battle Illfang the next day.
During the night, Asuna was eating dinner when Kirito came and joined her, prompting her to move away from him. Kirito gave Asuna a jar that tasted like a cream, which she enjoyed very much. Kirito told her that the jar was a reward he got from a quest and offered to show her the trick, but she quickly rejected the offer, stating that she didn't come to the town to enjoy food, but so that she can be herself rather than sit and wait at the first town. Even if she gets killed, she doesn't want to lose to the game. Kirito told her that he doesn't want a party member to die, and asked her to try to not die.
The next day, Kirito and Asuna were asked to target the boss's minions, the Ruin Kobold Sentinels. While walking to the boss, they planned strategies to defeat the helpers. The group entered the Floor Boss room where Illfang the Kobold Lord awaited along with his spawning minions, and the two factions charged at each other. Diavel led the raiding party and gave out commands on blocking and attacking the boss and his minions. During the battle, Kirito noticed Asuna's speed, remarking that he could not keep up with her blade. As the Boss's fourth HP gauge reached the red zone, Diavel ordered everybody to keep their distance, advanced ahead of the group, and approached the boss alone, which confused Kirito, as the original plan was for the raid group to surround it. However, Kirito quickly noticed that something was wrong when Illfang pulled out a Nodachi instead of a Talwar, which Illfang had used in the Closed Beta. Kirito told Diavel to stop and pull back, but he was too late, and the latter received a deadly combo from the boss' katana skills. As Diavel's health speedily dropped to 0, Kirito tried to give him a healing potion, but Diavel rejected it. In his last moment, Kirito learned that Diavel was after the Last Attack and was also a Beta Tester, and that he knew Kirito had been in the beta as well. He asked Kirito to defeat the boss for everyone before he shattered into many polygons.
With Asuna’s help, Kirito attempted to defeat the boss, with the same strategies they had used on the Ruin Kobold Sentinels. The boss proved to be fast and attacked Asuna first, but she dodged the hit, resulting in her cloak being destroyed, revealing her face. They continued with their tactics until Kirito made a mistake and got hit, slamming into Asuna. Agil saved them from receiving the final blow and told them to recover while the rest held the boss off. After they recovered, Kirito and Asuna give one last hit and Kirito received the last attack on the boss, defeating the boss with Kirito obtaining the Last Attack bonus item, the «Coat of Midnight».
Everyone celebrated their victory until Kibaou and his group reminded everyone that Diavel died, stating that Kirito let him die by withholding information that he knew the boss's attack pattern, and accused him of being a beta tester, not knowing that Diavel was a beta tester also. As everyone suspected each other of being beta testers, Kirito remembered Diavel's last words and gulped. Agil and Asuna tried to speak, but Kirito laughed and told the clearing group that they were better than those "newbies" (beta testers) who did not know how to level up, and boasted that he was not like the other testers because he reached higher floors than them and knew the boss's attack pattern because he fought monsters using katana skills on higher floors, and stated that he knew more than any information broker. Kibaou and many players in the clearing group then accused Kirito of being a cheater and one of them categorized him as a Beater (Beta Tester + Cheater), but Kirito expressed enjoyment in having the new title, and told the other players not to confuse him with other beta testers.
After equipping the «Coat of Midnight» to distinguish himself from the other beta testers, Kirito soon left the group behind and proceeded to open the gate to the next floor. Asuna briefly stopped him and asked how he knew her name, thus Kirito told her to look at her interface for the party screen. She then finally learned his name and felt dumb that she did not notice since it was there since the very beginning. Kirito then told Asuna that someone strong like her should find a guild she can trust as there were limits on what a solo player could do, after which he dissolved the party and headed to the 2nd Floor.
- «Wind Fleuret +4»
- Illfang the Kobold Lord
- Ruin Kobold Sentinel
- Pole Axe
- Two-Handed Battle Axe
- Argo's Information Guide
Known Sword Skills
- «Linear» - Asuna
- «Ukifune» (Floating Boat) - Illfang the Kobold Lord
- «Rage Spike» - Kirito
- «Tsujikaze» (Whirlwind) - Illfang the Kobold Lord
- «Vertical» - Kirito
- «Slant» - Kirito
- «Gengetsu» (Phantom Moon) - Illfang the Kobold Lord
- «Hiōgi» (Scarlet Fan) - Illfang the Kobold Lord
- «Whirlwind» - Agil
- «Tsumujiguruma» (Whirling Wheel) - Illfang the Kobold Lord
- «Sonic Leap» - Kirito
- «Vertical Arc» - Kirito (Last Attack)
- Aincrad Floor 1: Town of Tolbana
- Forest leading to the First Floor Labyrinth
- First Floor Boss Room
- The First Day side story was skipped entirely.
- Kirito originally met Asuna at the 18th level of the 1st Floor Labyrinth.
- Asuna's past life before borrowing her brother's console to play the game was omitted, as well as her one month character development from a kidnapped damsel in distress to a near-suicidal player who constantly ground her levels.
- «Argo the Rat» was not introduced and the fact that she was the second player on Kirito’s friend list and the publisher of the SAO guide books was omitted.
- The meeting for the boss raid took place after Kirito had lunch with Asuna in the light novel.
- The anime did not include Kirito's monologues about the danger of being known as a Beta Player; their life will be targeted as the one who helps release the death game. Also hurting other players is possible outside the safe boundary of the town and city.
- Asuna actually regained her desire for life after speaking to Kirito; who frequently taught her the beauty of the virtual world.
- The anime omitted Asuna's request to Kirito to use the bathroom in Kirito's rented farmhouse lodgings and subsequent bath and reflection, as well as Argo's visit to update Kirito on her client's offer on his Anneal Blade, which ended in her discovery of Asuna in the bath.
- Although the description in the novel states that Illfang the Kobold Lord was supposed to be covered in blue fur, both the light novel illustrations and the anime portrayed him with red fur.
- In the novel, Diavel did not aim for the Last Attack bonus by himself. His whole group was greatly damaged by one of Illfang's Sword Skills, before the boss started singling Diavel out.
- Several Sword Skills were omitted from the anime, including Kirito's Slant and Horizontal. Additionally, it was not shown that the boss used Hiōgi to kill Diavel, but it is shown when Illfang attempts to use the skill on Asuna and Kirito. «Tsumujiguruma» use against Diavel's party was also not shown, though the skill is shown later in battle, just before Kirito activates «Sonic Leap».
- In the novel, Kirito was one meter away from Diavel when he died and Kirito's conversation with Diavel was actually Kirito's inner-monologue. Diavel only managed to say an incomplete sentence to Kirito about defeating the boss before he shattered into polygons.
- Kirito trying to give a potion to Diavel was not part of the original story, as Kirito was too far away from Diavel to offer him a potion.
- In the anime, Kirito was shown to deflect several of Illfang's strikes with regular sword slashes, while in the novel, he used «Vertical» and «Horizontal» Sword Skills to do so and even then he had to boost the system assist for the skills to successfully deflect the powerful blows.
- In the novel, Kirito was sent flying through the room when he got hit with «Gengetsu» and was barely able to stand on his knees, while Asuna charged for the boss in his place. In the anime, he landed on Asuna and they both fell to the ground.
- In the novel, Kirito took five minutes to recover, until the boss's health reached below 30% and one of the tanks tripped, to register his state as "being surrounded", causing the boss to initiate «Tsumujiguruma». In the anime, the tanks were shortly overpowered by Illfang, who then activated the skill without a tank stumbling behind him.
- In the novel, Kibaou reacted to Diavel's fate only after the latter had died.
- In the anime Diavel was portrayed as a selfless «Beta Tester» who looked out for everyone, while in the novel, he tried to buy off Kirito's sword, so that the latter would have a harder time in getting a Last Attack on the boss.
- In the light novel, Asuna voluntarily removed her hooded cloak herself, helping to recapture everyone's morale after their leader's death, before charging at the boss, instead of the cloak being removed by Illfang's attack.
- There was no mention of Kirito's habit of Last Attacking the boss.
- There was no mention of Diavel and Kibaou being cohorts. Kibaou had tried to purchase Kirito’s «Anneal Blade +6» at an outrageous price in the novel.
- There was no demonstration of Kirito's leadership as he directs the seven raiding parties against the boss’s actions.
- It was originally a player of Diavel's group, named Lind, who accused Kirito of allowing Diavel's death by withholding information in the novel, rather than Kibaou.
- In the novel, the "Beater" term was derived from the overlapping voices crying "Beta Tester" and "Cheater". In the anime, a single voice created the portmanteau.
- There was no display of the in-game messaging feature, which players can use to send and receive messages to their known acquaintances.
- The opening scenery of the 2nd Floor was not shown, thus the event where Asuna asks Kirito how he knew her name was shown while they were still on the stairs.
- "We need to defeat the first boss, reach the second floor, and tell everyone waiting in the Town of Beginnings that it is possible to beat this game." - Diavel
- "When this game started, the only thing I thought about was surviving. However Diavel, you were a beta tester. But you never abandoned the other players." - Kirito
- "You tried to do what I could not" - Kirito
- "A beta tester? I wish you wouldn't compare me to those newbies. Most of the thousand beta testers were beginners who didn't even know how to level up. You guys are much better than they are. But I'm not like them, I made it higher than all of them. [...] That's right I am a Beater. From now on, don't confuse me with the other testers." - Kirito
- "A beta tester and a cheater, you're a Beater!" - Members of the Clearing Group