Aincrad (アインクラッド, Ainkuraddo?) is the 1st book in the Sword Art Online Light Novel series, published on April 10, 2009 in Japan.
A solo player named Kirito, who had the luck-of-the-draw to once play the beta version of the first VRMMORPG, «Sword Art Online» (SAO) , was among the 10,000 players who were trapped inside of the game during the first day of its official service. The only way for them to escape is by clearing all the floors of Aincrad, the floating castle that is the setting for the game, and defeating the final boss. Death in-game means death in the real world, due to the NerveGear, a console that simulates the in-game character controls by redirecting brain signals. Two years after the start of the death game, out of the original ten thousand players at the start, less than seven thousand remain with twenty-five floors left to clear.
A huge castle made of stone and steel floating in an endless sky. That was all this world was.
It took a various group of craftsmen one month to survey the place; the diameter of the base floor was about 10 kilometers, large enough to fit the entirety of Setagaya-ku within. Above, there were 100 floors stacking straight upwards; its sheer size was unbelievable. It was impossible to even guess how much data it consisted of.
Inside, there were a couple of large cities along with countless small scale towns and villages, forests and plains, and even lakes. Only one stairway linked each floor to another, and the stairways existed in dungeons where large numbers of monsters roamed; so discovering and getting through was no easy matter. However, once someone made a breakthrough and arrived at a city of the upper floor, the «Teleport Gates» there and of every cities in the lower floors would be connected making it possible for anyone to move freely through these levels.
With these conditions, the huge castle had been steadily conquered for two years. The current front line is the 74th Floor.
In the 74th Floor Labyrinth, Kirito had a battle with a Level 82 «Lizardman Lord». After defeating the monster with his four-hit Sword Skill, Horizontal Square, he recollected what occurred two years ago.
Klein asked for Kirito's guidance after presuming that the latter was among the one thousand participants of the «Sword Art Online Closed Beta». After Klein successfully defeated a «Frenzy Boar», he tried to log out because he ordered pizza. Failing to find the logout button, Kirito and Klein discussed the implications of the "unable to logout bug".
Without warning, the two were both teleported to the central plaza of the «Town of Beginnings». The Game Master Kayaba Akihiko informed them that the only way to log out was by clearing all one hundred floors of the floating castle of «Aincrad», and that death in-game spelled death in real life.
Kirito, realizing that there would be shortage of monsters near the «Town of Beginnings», urged Klein to leave the city with him. Klein then asked Kirito whether they could take his friends along. Kirito, unable to bear the heavy burden of Klein and his friends' lives, wordlessly disagreed. They parted ways after Klein decided to help his real life friends.
Almost a month into the game, 2,000 players had died. The remaining players were divided into four groups: players who could not accept Kayaba's terms and thus waited within Town of Beginnings for outside help, «The Army» members, players who squandered their money and later joined The Army, and players belonging to various guilds. Only a mere fraction of those were solo players.
While returning home, Kirito successfully killed a super rare monster, «Ragout Rabbit», and teleported to Algade to sell the «Ragout Rabbit's Meat». He later decided against selling the Meat after talking with the shop owner Agil and meeting Asuna the «Flash»; sub-leader of the guild known as the «Knights of the Blood». He agreed with her cooking the ingredient in her house in exchange of giving her half the meat. Asuna then ordered her subordinates that she will be leaving for the day, displeasing her bodyguard, Kuradeel. Kuradeel directed his anger to Kirito after realizing he is a «Beater» (a combination of a «Beta tester» and «Cheater»). Asuna, disgusted with Kuradeel's actions, ordered him to leave once more. She ended the conflict by leaving with Kirito through the crowd.
Kirito journeyed with Asuna to her home in the 61st floor to cook the «Ragout Rabbit's Meat». Upon arriving, Asuna prepared the meal with her maxed out cooking skill. After enjoying the gourmet meal with the taste synthesized by the «Taste Reproduction Engine», Asuna later persuaded Kirito into forming a party with her.
An unhappy Kirito was waiting for the late arriving Asuna at their specified meeting place. Asuna, running away from her bodyguard Kuradeel, bumped into him while using a Teleportation Crystal. Kuradeel, who strongly disagreed of her recent actions, attempted to take her back to their guild headquarters. Kirito intervened for Asuna’s sake and enters a 1-on-1 duel against Kuradeel. Kirito easily won the match by breaking Kuradeel’s decorated two-hand sword using the Outside System Skill, «Arms Blast». Kuradeel, enraged by his defeat, threatened to kill Kirito. Asuna ordered Kuradeel to return to «Granzam» to prevent things from escalating any further, and later apologized to Kirito for the trouble.
Kirito and Asuna were discussing each other’s taste in clothing until Kirito noticed the movement of numerous flashing green cursors on his virtual scanner. The two of them hid themselves behind the trees, under Kirito's coat, as they watched the 12 players from the guild «The Army» march past. Asuna then informed Kirito about the change in behavior of «The Army». Both feared that «The Army» might try the suicidal task of challenging the yet to be discovered boss of the 74th Floor with no knowledge of the boss and with just 12 members. After the battalion moved past them, the two headed into the Floor's Labyrinth.
The «Knights of the Blood» was known as the best guild in over a year; the leader of the guild, the «Man of Legend» Heathcliff, and the sub-leader Asuna the «Flash» were both renowned as two of the best warriors in Aincrad. Kirito thought about this as he was teaming up with Asuna against the common skeleton enemy: the «Demonic Servant»; both displayed their excellent teamwork with a skill known as «switching» against their common foe. As they mapped the dungeon, they soon came across the eerie-looking door of the boss room. After a few minutes of hesitation, they peeked inside and look for the dweller of the dark room; there, their eyes met with «The Gleam Eyes», the boss of the 74th Floor.
Asuna and Kirito took a break at the safe zone of the labyrinth; both of them eating Asuna's handmade sandwiches. After tasting a flavor that was similar to something to the outside world, Kirito took Asuna's hand and put her fingers in his mouth. Klein entered the safe zone and saw Kirito and Asuna together. Their conversation was later interrupted by the presence of the «The Army» troops. After claiming Kirito’s mapping data, «The Army» troops marched away and into the labyrinth. Kirito and the group decided to follow after them after worrying that «The Army» may challenge the boss by themselves despite their earlier warning.
«The Army» had challenged the boss and was suffering from their mistake; crystal usage was prohibited in the boss room and «The Gleam Eyes» was blocking the exit. Kirito and the others entered to provide support. Backed into a corner, Kirito was forced to use his secret «Unique Skill», «Dual Blades». Never had anyone seen Kirito use such a skill like that, and Kirito managed to defeat the floor boss, with only a miniscule amount of Hit Points to spare.
The fallen Kirito awoken to find Asuna crying while holding him. The remaining members of «The Army» returned to their base to report the incident, and the honour of establishing the link to the next floor was left to Klein and his guild. Asuna decided to take a momentary break from «KoB» and thus planned to stay with Kirito for a little longer.
As the hidden unique skill «Dual Blades» was now known to the public and thus with a sudden rise in fame, Kirito went into hiding from the persistent crowd at the second floor of Agil’s shop, waiting for Asuna to return from the «KoB». A new problem arose when Heathcliff wishes to duel with the now famous Kirito for the sake of Asuna.
The grand event of the duel featured the two «Unique Skill» wielders: the «Dual Blades» vs. the «Holy Sword». Kirito accepted Healthcliff’s challenge under the conditions that Asuna will be released to him if he wins, and joining the «KoB» if he loses. The match proceeded with each other whittling one another’s life-span, with varying chances that the winner can be either one. The match ended with Kirito’s loss, as «the Living Legend» performed an impossible move in which he moved at a speed that momentarily broke the game.
As Kirito was a man of his word, he joined the «KoB»; already disliking the blinding white uniform that was in contrast to his usual black coat. Much to Asuna’s surprise, Kirito confessed about the tragic end of his first guild, the «Moonlit Black Cats», still believing that he was the trigger of their demise. Feeling his sorrow, Asuna comforted Kirito during his time of guilt.
On the first day on the job, Kirito had to attend a mandatory training course to present his skills. To his dismay, Kirito discovered that he had to work alongside with the last person he wanted to see: Kuradeel.
After Kirito relinquished all of his crystals following Godfree’s order, the group adventured to the 55th Floor's Labyrinth. At the time of their break, Kuradeel attempted his assassination after lacing the drinking water with paralysis poison, killing Godfree and a second KoB member until the paralyzed Kirito was left alone. Before assaulting Kirito's Hit Points, Kuradeel revealed himself to be one of the last remaining members of the worst Player Killing guild: «Laughing Coffin».
Despite the paralysis, Kirito struggled near to his death against Kuradeel and was rescued by Asuna, who had arrived in the nick of time to allow Kirito to recover. Demonstrating why she earned the name of the «Flash», she reaped Kuradeel's health near to its end before allowing him to surrender. However, Kuradeel took this moment of hesitation to overpower Asuna and kill her. To protect Asuna, Kirito ended Kuradeel’s life by stabbing deep into him with his hand, using the Martial Arts skill «Embracer». At the end, Kirito told Asuna that he would offer his life to her, and will stay with her to the very end.
It was revealed that Asuna was monitoring the map while waiting within the KoB headquarters. Asuna and Kirito reported to Heathcliff about the incident, and temporarily left the guild with his permission. As Kirito did not want to be alone at the moment, he carelessly told Asuna that he wanted to be with her that night, which led to a comical chain of events that drew some attention to an interesting option on their virtual menu screen called «Moral Code Removal». After some time, Kirito finally unveiled his feelings to Asuna, and then he made his proposal to her for marriage.
Kirito and Asuna, now in the relationship of marriage in Aincrad, spend their newly-wed life at a small, round cottage on the 22nd Floor. Once again, both announced their love for one another.
Ten days have passed; both Kirito and Asuna, having pushed aside their fighting skill for the moment, decided to train their domestic skills; Kirito on fishing, and Asuna on sewing. As luck would have it, Kirito seemed to have spent it all in getting Asuna to marry him as no fish would bite. They soon met a fisherman name Nishida, and decided to help him carry out a fishing event on a later day.
It was the day of the fishing event; not only was Nishida, Kirito, and Asuna were present, but a crowd was waiting attentively for the appearance of the local fish god. Nishida uses his highly-trained fishing skill to get the bite, and then «switches» for Kirito’s superior strength. What they caught, however, was an enormous fish that could walk on land. Asuna soon killed the monster with ease. The event ended and so did their honeymoon, as they were requested to attend the boss raid by Heathcliff the following day.
Kirito and Asuna returned to the «KoB» headquarters to learn of the demise of a scouting party from Heathcliff; the room of the 75th boss was discovered, however no intel about the boss was obtained. Upon passing the gate, the boss room will isolate itself and the use of teleportation crystal will be prohibited. Despite the applied grim conditions, Heathcliff still planned to attack the boss with his strongest members and hope for the assistance of Kirito and Asuna.
Klein and Agil were amongst the group of high level players who gathered for the boss raid; including Kirito, Asuna, and Heathcliff. The tension rose as the man of legend led the group through the gate of the rare «Corridor Crystal», they trespassed into the boss room with 32 players and awaited the gate to close behind. Within the isolated room, the battle commenced against the skeletal centipede that could kill a player with one strike; «The Skull Reaper».
The battle continued for over an hour until the fall of «The Skull Reaper»; the deadliest foe so far who easily eliminated 14 players. Everyone grieved about whether it was possible to complete the game, as the fatalities and difficulties will certainly rise in the coming battles. Suddenly, thanks to Kirito's intuition, the true identity of the immortal Heathcliff was discovered to be the creator, Kayaba Akihiko. After immobilizing everyone with the authority of the system administrator, Heathcliff decided to challenge Kirito with a one-on-one duel to the death for everyone’s freedom, which Kirito boldly accepted.
The battle raged on with the unyielding actions of Kirito and Heathcliff; both accelerating their skills to an intense speed; and it continued until Kirito committed the mistake of trusting a skill guided by the system. As the match drew near to a close, an impossible event occurred: the last attack that would have ended Kirito’s life was redirected onto the supposed immobilized Asuna, who shielded him. The attack depleted the last of her remaining health, and as the one truth imagined in this world, she perished in Kirito’s arms.
With the loss of Asuna, Kirito lost his state of mind and fought with little care for his own life. After Heathcliff pierced Kirito with his blade and depleted the last of his Hit Points, the dying Kirito performed his last act by using Asuna's sword to kill Heathcliff. The battle resulted with the deaths of the two duelists and the friends of Kirito witnessing the destruction of both bodies. The infamous last boss was eliminated and thus the game was cleared.
Kirito found himself staring at the steel castle in another world alongside Asuna; watching as the game executed the Final Phase; the destruction of Aincrad. They were soon interrupted by the presence of Kayaba Akihiko; the man who started it all. After explaining his motives for the death game, he left the two lovers Kirigaya Kazuto and Yuuki Asuna, for the departed world.
Kirito was finally freed from the game. After finding himself in the hospital, he left his bed, with his body frail and weak, but he would not rest until he had Asuna back in his arms.
- The original web novel states that 50,000 players were captured within SAO. The Light Novel publication changed this to 10,000.
- In the volume, Kirito first encountered Klein on the first day of the SAO official service, but in the web version, they first met in September 2013, three months before the Christmas Event.
- In the web version of the Aincrad arc, the NerveGear did not fry the player's brain when they died in the game. Instead, if players were disconnected from the server for a designated amount of time, died in game, or had their NerveGear removed without following proper procedure, force disconnection would be caused and players' consciousness would disappear and their body would become eternally vegetated. However, the web version of Phantom Bullet arc had a statement related to a high output of microwaves from the NerveGear causing damage to parts of the brain.
- The web version categorized all virtual reality machines as part of the NERv Direct Linkage Environment System (NERDLES) and subsequently explained how the NerveGear was developed based on a prototype of its kind which was released in 2006. The published version removed this explanation and instead included the new scenes of Kirito meeting Klein and training him.
- In the web version, during his announcement, Akihiko appeared as a floating hologram of his face. The published version changed this to him appearing as a cloaked figure with no body.
- Chapter 14 in the light novel had a few details changed, from when Kirito was recalling his time with Sachi.
- In the light novel, after bringing up how Sachi and him were similar to each other, he pointed out that she one day came to him and admitted her fear of death. However, the web novel did not mention her telling him this.
- In the web version of this passage, Kirito recalled how the two often spent time together, outside of simply training, but this was omitted in the light novel.
- These changes seem to indicate that in the web novel, both Kirito and Sachi were significantly closer. This is further reinforced by a Popularity Contest Q&A, during the web novel's run, where Kirito says that his first love was "Someone who was in the Moonlit Black Cats," likely referring to Sachi.
- In the original web novel version for Aincrad, there were mentions about Kirito considering the relationship between Sachi and Keita being above the usual friendship level. However, this was removed from both the published version as well as the web version of EX06 Red-Nosed Reindeer.
- In the original web novel, Asuna did not hesitate to kill Kuradeel when he began to beg for his life. In the light novel and anime adaption, this was changed so that Kirito would save Asuna, after she had a moment of doubt, allowing Kuradeel an opening to disarm and then attack her.
- In the web version, there were two lines that mention that Kirito and Asuna did "everything that the system permitted" in the context of the Moral Code switch, which led to the prologue of a doujinshi non-canon story named "16.5". Those two lines were removed from the published version.
- The mention about the NerveGear's function of pleasure regeneration in the web version's chapter 18 has been removed from the published version.
- The one hour of disconnection occurred a few days after the game started in published version, while in the web version, it was around ten hours of disconnection that occurred a few weeks after the game started.