Clad in desert pink and the size of a mere child, the infamous Pink Devil mercilessly hunts down other players in the firearm-centered world of the virtual reality game Gun Gale Online. But in real life, this feared player killer is not quite who anyone would expect. A shy university student in Tokyo, Karen Kohiruimaki stands in stark contrast to her in-game avatar—in fact, she happens to stand above everyone else too, much to her dismay. Towering above all the people around her, Karen's insecurities over her height reach the point where she turns to the virtual world for an escape. Starting game after game in hopes of manifesting as a cute, short character, she finally obtains her ideal self in the world of Gun Gale Online. Overjoyed by her new persona, she pours her time into the game as LLENN, garnering her reputation as the legendary player killer. However, when one of LLENN's targets gets the best of her, she ends up meeting Pitohui, a skilled yet eccentric woman. Quickly becoming friends with Karen, Pitohui insists that LLENN participates in Squad Jam, a battle royale that pits teams against one another, fighting until only one remains. Thrust into the heated competition, LLENN must fight with all her wit and will if she hopes to shoot her way to the top.

Ever since the release of the innovative NerveGear, gamers from all around the globe have been given the opportunity to experience a completely immersive virtual reality. Sword Art Online (SAO), one of the most recent games on the console, offers a gateway into the wondrous world of Aincrad, a vivid, medieval landscape where users can do anything within the limits of imagination. With the release of this worldwide sensation, gaming has never felt more lifelike. However, the idyllic fantasy rapidly becomes a brutal nightmare when SAO's creator traps thousands of players inside the game. The log-out function has been removed, with the only method of escape involving beating all of Aincrad's one hundred increasingly difficult levels. Adding to the struggle, any in-game death becomes permanent, ending the player's life in the real world. While Kazuto Kirito Kirigaya was fortunate enough to be a beta-tester for the game, he quickly finds that despite his advantages, he cannot overcome SAO's challenges alone. Teaming up with Asuna Yuuki and other talented players, Kirito makes an effort to face the seemingly insurmountable trials head-on. But with difficult bosses and threatening dark cults impeding his progress, Kirito finds that such tasks are much easier said than done.

The Soul Translator is a state-of-the-art full-dive interface which interacts with the user's Fluctlight—the technological equivalent of a human soul—and fundamentally differs from the orthodox method of sending signals to the brain. The private institute Rath aims to perfect their creation by enlisting the aid of Sword Art Online survivor Kazuto Kirigaya. He works there as a part-time employee to test the system's capabilities in the Underworld: the fantastical realm generated by the Soul Translator. As per the confidentiality contract, any memories created by the machine in the virtual world are wiped upon returning to the real world. Kazuto can only vaguely recall a single name, Alice, which provokes a sense of unease when mentioned in reality. When Kazuto escorts Asuna Yuuki home one evening, they chance upon a familiar foe. Kazuto is mortally wounded in the ensuing fight and loses consciousness. When he comes to, he discovers that he has made a full-dive into the Underworld with seemingly no way to escape. He sets off on a quest, seeking a way back to the physical world once again.

Despite the defeat of Quinella—the pontifex of the Axiom Church—things have not seemed to calm down yet. Upon contacting the real world, Kazuto Kirito Kirigaya finds out that the Ocean Turtle—a mega-float controlled by Rath—was raided. Due to a sudden short-circuit caused by the raiders, Kirito's fluctlight is damaged, leaving him comatose. Feeling insecure about the people at the Axiom Church, Alice brings the unconscious Kirito back to their hometown—Rulid Village, disregarding her banishment due to an unabsolved crime. Now, Alice is living an ordinary and peaceful life close by the village, wishing for Kirito to wake up. However, tragedy strikes when Alice notices that the Dark Territory has already started to invade the Human Empire. Reassuming her previous alias, Alice Synthesis Thirty, she promises to defeat the Dark Territory in order to defend the world that Kirito and Eugeo worked so hard to protect.