Bullet of a Phantom
After checking the map, Kirito finds that twenty-four players had already been killed, while only Yamikaze and himself are shown on the map. Seeing as, even accounting for Sinon, Death Gun, and Pale Rider, the numbers of those killed and those who are still alive did not match the total, he speculates that Death Gun had more than one accomplice in charge of the killings in the real world. Fearing that Yamikaze might also be a target, Kirito and Sinon decide to set up the former as bait, while Sinon snipes Yamikaze and Death Gun from a distance when they arrive. Sometime later, while Yamikaze is closing in on Kirito, Death Gun attempts to kill Kirito himself. Sensing his intent to kill, Kirito manages to sense where he would be shot from and barely manages to dodge the bullet. Noticing a sniper shot, Yamikaze immediately hides behind an obstacle for cover, but he is then shot by Sinon and killed. Sinon then turns her attention to Death Gun, but, as she had already fired her first shot, which wouldn't be detected, Death Gun is able to see her targeting him. The two of them fire at each other at the same time and, while Death Gun manages to destroy Sinon's scope, she manages to destroy Death Gun's weapon. However, as Kirito is about to strike Death Gun, the latter pulls out an estoc and counters the attack. After having a conversation with Kirito, Death Gun begins assaulting him with overwhelming speed.
Aired 20/09/2014EP 12 - Bullet of a Phantom

Sword Art Online II
One year after the SAO incident, Kirito is approached by Seijiro Kikuoka from Japan's Ministry of Internal Affairs and Communications Department "VR Division" with a rather peculiar request.
That was an investigation on the "Death Gun" incident that occurred in the gun and steel filled VRMMO called Gun Gale Online (GGO). "Players who are shot by a mysterious avatar with a jet black gun lose their lives even in the real world..." Failing to turn down Kikuoka's bizarre request, Kirito logs in to GGO even though he is not completely convinced that the virtual world could physically affect the real world.
Kirito wanders in an unfamiliar world in order to gain any clues about the "Death Gun." Then, a female sniper named Sinon who owns a gigantic "Hecate II" rifle extends Kirito a helping hand. With Sinon's help, Kirito decides to enter the "Bullet of Bullets," a large tournament to choose the most powerful gunner within the realm of GGO, in hopes to become the target of the "Death Gun" and make direct contact with the mysterious avatar.
(Source: Crunchyroll)