Versus

Versus (バーサス) is the «Sword Art Online» and «Accel World» crossover published on December 10, 2011 in volume 10, chapter 3 of Accel World. It was also adapted into one of the tracks of Accel World + Sword Art Online Drama CD  as well as part of the Accel World manga Volume 5, from chapter 18 to 20.

Summary
Kazuto (Kirito) was on a part-time job to test out the 4th generation FullDive machine created by Rath. He was told that other users had seen a ghost and so he was there to check if it was true.

During the dive he saw a robotic figure. He instinctively grabbed the sword hung on his back, only to discover that he was his avatar from Sword Art Online, Kirito the Black Swordsman. He looked up and saw a timer, health bar, stamina gauge on both sides of his vision, his login ID "KIRITO" on the left side and his opponent's ID, SILVER CROW, on the right.

He tried to communicate and walked slowly, forgetting that he was still holding his sword. Silver Crow suddenly rushed and tried to kick him, but Kirito dodged it swiftly. He drew out his Elucidator and, while remembering the feeling of one of his old beloved swords, swung his sword without thinking, cutting Silver Crow's right shoulder. Silver Crow began using his special move and flew out. Confused, Kirito looked up and saw that Silver Crow's stamina gauge, which was full before, had decreased by around three percent. Kirito realized that this bar indicated the special move and that his special move must be a Sword Skill from Sword Art Online.

He tried to see if his guess was right and tried to do a basic one-handed straight Sword Skill «Sonic Leap», causing the sword to growl faintly and the stamina gauge shining part blinked, indicating that the gauge was not full enough. Kirito also realized that he was the one intruding and Silver Crow must have played this game daily and the 4th generation experimental machine's quantum circuit intruded.

Silver Crow rushed in again while lowering his body and focused on the tip of the sword and, while lowering his body even further, shortened the distance by 10 meters at once. Kirito tried to slash his sword upwards to intercept him, who was leaning forward, however Silver Crow opened his left wing, causing his body to rotate 90 degrees, only getting a shallow cut on his chest armor and he stepped on his left foot, trying to make an uppercut to his abdomen, but Kirito dodged it, the attack only grazing his left shoulder, though Silver Crow used his left fist to make a short hook, damaging him. Silver Crow also used his right knee to successfully attack him and he pinned Kirito's left arm with his right and aimed short strikes with his left, making Silver Crow think that the sword would be useless at this range. However, he realized that Kirito did not have his sword and he had his right hand's fingers spread out. In a smooth, but terribly fast movement, Kirito touched Silver Crow's chest with his now emitting orange light right fist, making Silver Crow realize that he was using his special move. There was a great impact on to Silver Crow, as he was repelled backwards, though the damage was not great. Suddenly Kirito rushed in empty handed and Silver Crow was wondering what he would do. Silver Crow realized that his right hand was still going, indicating that the special move was not over, and Kirito grabbed hold of his sword, which had been thrown into the air and was now in the colour of a blinding flame, and Kirito slashed Silver Crow in a straight line.

There was an explosion which pushed Silver Crow to the back and to the right. Kirito looked up again and saw that the blow he received did damage that was equal to 15% of his health, while the damage that he dealt to Silver Crow about 30% of his health. Kirito then looked at the rubble Silver Crow was in and tried to perform a sneak attack, however the rubble was scattered and Silver Crow was not in sight. Kirito found out that Silver Crow's stamina bar was now 30% and still decreasing, indicating that he was now using his special move. Kirito prepared himself for his front, back, sides and underneath, however Silver Crow was in the air. Kirito realized that he had wings and tried to jump and get out of the way of the impact, but Silver Crow moved with him and so he tried to defend from the sharp toe with his sword, but it was impossible and got dive kicked into his shoulder. After the attack Silver Crow looked at Kirito's health and found out that it was just below 50% and into the yellow.

Before Kirito's right arm recovered, Silver Crow spread his wings again and rushed in again to swing a big roundhouse kick diagonally upwards, however Kirito blocked it using his left hand and other sword, the Dark Repulser. Kirito used both swords to attack Silver Crow. He then checked Silver Crow's health and found out that his opponent had 40% remaining. Silver Crow then opened his wings, waiting to counter-attack Kirito. Kirito seeing this, begins to charge at the speed of a bullet through a cannon and use Dual blades rush Sword Skill, «Double Circular». Kirito, in front of Silver Crow, rotated his body upwards and used his black sword to slash upwards furiously, damaging Silver Crow's left wrist armor and making a rip in it. Kirito then used his white sword to thrust into his neck. Silver Crow caught it by letting the sword penetrate his hand and catching Kirito's fist. Silver Crow then flew and, during acceleration, turned around and threw Kirito to the floor. Silver Crow did a long range roundhouse kick, hitting Kirito even through his block. Silver Crow rushed in again and Kirito blocked with both of his hands, however Silver Crow violently headbutted Kirito's chest. Kirito then began to prepare for his special attack and Silver Crow rushed downwards while Kirito jumped to him. Just as both attacks made contact with each other, Kirito's body turned into white light and he was disconnected.

In the end, Kazuto talked with Suguha, describing how Silver Crow's flying ability was different from ALfheim Online, where their flight was not true flight, but rather just an imitation of what it could become, and that the fight had ended in a draw. Meanwhile, Haruyuki told the story of his adventure to Kuroyukihime. He told her that he had faced a strange opponent, who was stronger than him, and that he would have lost the battle, if the opponent had not disconnected just before the conclusion.