Death Chaser
Before Death Gun could shoot Sinon, he is interrupted by Kirito, who shoots him in the shoulder with a sniper rifle and then throws a smoke grenade, which forces him to retreat. Kirito then grabs the stunned Sinon and flees to a nearby buggy and horse rental point. While commandeering a buggy, he orders Sinon to shoot the only functional mechanical horse to make it unusable. However, Sinon is unable to exert force on the trigger, and Death Gun catches up and takes control of the mechanical horse. During the subsequent chase, Death Gun fires at Kirito and Sinon with his pistol, terrifying the latter. When Sinon tries to shoot at Death Gun, Kirito is forced to help her pull the trigger. Though the shot misses Death Gun, it hits the fuel tank of a truck, which explodes and forces Death Gun to abandon his horse, allowing Kirito and Sinon to escape. The two then drive into the desert, where they find a cave that they hide in to avoid the next satellite scan. Inside, both Sinon and Kirito confide to each other that they have killed someone in the past.
Aired 06/09/2014EP 10 - Death Chaser

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)