In the year 2022, virtual reality has progressed by leaps and bounds, and a massive online role-playing game called Sword Art Online (SAO) is launched. With the aid of "NerveGear" technology, players can control their avatars within the game using nothing but their own thoughts. Kazuto Kirigaya, nicknamed "Kirito," is among the lucky few enthusiasts who get their hands on the first shipment of the game. He logs in to find himself, with ten-thousand others, in the scenic and elaborate world of Aincrad, one full of fantastic medieval weapons and gruesome monsters. However, in a cruel turn of events, the players soon realize they cannot log out; the game's creator has trapped them in his new world until they complete all one hundred levels of the game. In order to escape Aincrad, Kirito will now have to interact and cooperate with his fellow players. Some are allies, while others are foes, like Asuna Yuuki, who commands the leading group attempting to escape from the ruthless game. To make matters worse, Sword Art Online is not all fun and games: if they die in Aincrad, they die in real life. Kirito must adapt to his new reality, fight for his survival, and hopefully break free from his virtual hell. [Written by MAL Rewrite]

A year after escaping Sword Art Online, Kazuto Kirigaya has been settling back into the real world. However, his peace is short-lived as a new incident occurs in a game called Gun Gale Online, where a player by the name of Death Gun appears to be killing people in the real world by shooting them in-game. Approached by officials to assist in investigating the murders, Kazuto assumes his persona of Kirito once again and logs into Gun Gale Online, intent on stopping the killer. Once inside, Kirito meets Sinon, a highly skilled sniper afflicted by a traumatic past. She is soon dragged in his chase after Death Gun, and together they enter the Bullet of Bullets, a tournament where their target is sure to appear. Uncertain of Death Gun's real powers, Kirito and Sinon race to stop him before he has the chance to claim another life. Not everything goes smoothly, however, as scars from the past impede their progress. In a high-stakes game where the next victim could easily be one of them, Kirito puts his life on the line in the virtual world once more.

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.

In the land of Terra, natural disasters of unknown causes have been occurring irregularly in many areas. Therefore, the majority of the people, in order to escape those natural disasters, came to live in mobile cities developed over the years. The Originium left behind at the site of such Catastrophes, has led to the rapid progress of civilization due to their immense energy. But it also brought something else with it — an incurable disease called Oripathy. Because the bodies of those with Oripathy gradually crystalize and become a new source of infection at the time of death, in many countries, the Infected are subject to persecution under regimes of segregation and forced labor. Those who were oppressed by the governments are starting to rebel. Rhodes Island, a pharmaceutical company researching a cure for Oripathy, takes up their arms and starts a conquest trying to save all the people from the disease.