A full year has elapsed since the adventure in Sword Art Online concluded, followed by another ten months of peace after the incident in ALfheim Online. However, strange events have begun to occur once more, this time in the VRMMO game known as Gun Gale Online (GGO). Two players have been shot by an individual cloaked in a mantle who calls himself "Death Gun." Strangely, after their in-game deaths, these players disconnect from the game and are then found dead in reality days later. In light of these events, Kikuoka Seijirou from the VR Crimes Division contacts Kirigaya Kazuto to investigate a connection between the in-game and real-life deaths. It is discovered that Death Gun specifically targets the highest-ranked players, leading Kazuto to take action by transforming his ALfheim Online character into one suitable for Gun Gale Online, and enlisting in the prestigious Bullet of Bullets tournament to try and catch the mysterious killer.
