One year has passed since the "SAO" incident. One day, Kirito received a strange request from Seijiro Kikuoka, the "virtual class" of the Ministry of Internal Affairs and Communications. That was the "Death Gun" incident that suddenly occurred in the VRMMO "Gun Gale Online" filled with guns and steel. Players who are hit by a mysterious character holding a jet-black gun will also "die" in the real world... Unable to refuse, Kirito agreed to help investigate. Although he was doubtful about the physical impact of the "virtual world" on the "real world", he still logged in to "GGO". Kirito wanders around in an unfamiliar game in search of clues about the "Death Gun". To his aid is a girl who is accustomed to wielding a large rifle "Hecate II" - Sinon. A new story is about to unfold!
