The world of Sword Art Online: Integral Factor is replete with unique lore with certain details differing from the original story of Sword Art Online.
The MC meets Koharu on the last day of Sword Art Online's beta test and teaches her on how to play the game. Kirito is introduced after saving them from a strong monster encounter. After he briefly gives them tips about fighting monsters and leaves, the beta test soon ends and the MC and Koharu say their goodbyes.
Koharu eventually meets up with the MC again and they continued practicing. Klein and Kirito finds them in the fields practicing and help teach them about fighting.
Similar events play out like the overall SAO storyline. Klein and others discover that they can't logout and are teleported to the Plaza. Kayaba Akihiko announces his new rules and the message of Sword Art Online being a death game. The game becomes a fight for survival among the 10,000 players. The Mirror item reverts everyone's avatars to their real physical appearances using information from the NerveGear's facial and body scans; Koharu kept her real look on her avatar for purposes of trying on clothing in VR, so she changed little in appearance. She and many other players become distressed by the situation. The MC and Klein take her out of the plaza while Kirito quickly heads to the next town. While both were helping with Koharu, Argo the Information Broker meets them. Klein leaves to meet up with his other friends in the Plaza.
Argo gives an informative tutorial to the MC and Koharu on SAO's (or SAO:IF's) basic gameplay mechanics. Later, both encounter Miyurin, Ulrik, and Kibaou who requests some needed fetch Quests. Both also encounter Sachi while preparing to eat and later Diavel who wishes to recruit the MC and Koharu for the floor boss fight. They travel to the Tolbana Amphitheater to discuss with him about the upcoming fight.
During the boss fight, Diavel rushes in to get the last attack bonus but is thrown off by the boss's new weapon and attack pattern. Before he was dealt the killing blow, the MC saves Diavel by swiftly blocking the boss's attack while Kirito assists. Despite Diavel surviving the boss fight, Kibaou accuses Kirito for withholding information about the boss after figuring out he was a beta tester. Kirito decides to portray himself as a Beater in order to divert negative behavior towards beta testers. Diavel makes the decision to step down as the army's leader out of guiltiness.
Diavel's army splits up into two major groups, the Aincrad Liberation Squad led by Kibaou and the Dragon Knights Brigade by Lind, an ambitious follower of Diavel.
Both parties decide to ally with each other during the fight against the floor boss. Although having great resentment towards Kirito, he and the others join the fight as a support squad to also ensure he doesn't get the last attack bonus. Kirito ends up having to join the main squad and gets the last attack bonus, deepening the grudges from the ALS and DKB parties.
The MC and Koharu enter a story quest involving a long Elven conflict that continues along the next several floors.
Forest Elves and Dark Elves have been in war for many years due to their long history of hatred between each other. Sometime during the conflict, the sacred relic key, the Jade Key, was stolen from the Forest Elves and they believe the Dark Elves have taken it. The Forest Elf warrior Kales'Oh and his group was sent to find the Jade Key from the Dark Elf warrior Kizmel and her group.
Both join the Dark Elves side to save Kizmel from an encounter with Kales'Oh. They help assist her and her weakening army from Forest Elf attacks. Along the quest, the group meets up with Leafa, a player who is mistaken as a Forest Elf.
As everyone arrives to the 4th floor, Kirito states that in the beta the floor had a more desert-like landscape instead of a large lake surrounded by forest. Before the MC and Koharu set off to explore the floor, they encounter the blacksmith Lisbeth and helps her collect some materials.
The MC and Koharu later meet up with Kizmel again at a hidden Dark Elf fortress and further talk about the Elven conflict. Kizmel at the end of the conversation gave them a task to find Tuoli, a young Dark Elf soldier who has the essential item, the Lapis Key. They head to the labyrinth and found Tuoli standing near the entrance, who is inflicted with a poisonous curse. Before she could give the key, they are ambushed by Fallen Elves, elves who are "traitors who are no longer graced by the Sacred Tree." As they were about to take the key, the player Yuuki jumps in to assist the MC and Koharu to defeat the Fallen Elves. Tuoli fulfills her last task by giving the Lapis Key to them.
Another task was given by Kizmel about having a ceasefire with a Wood Elf Commander on the same floor by convincing him with a Fallen Elf written note. The MC, Koharu, and Yuuki goes and seeks out the commander.
These are the conversations of each floor. Lore Conversations
- On Floor 1 during the fight against Illfang the Kobold Lord, Diavel is saved by the MC from Illfang's unexpected attack rather than dying from it.
- Leafa, Yuuki, and Sinon never originally appeared inside of Sword Art Online as they only first appeared in Alfheim Online / Gun Gale Online.