Byman Hagard fought in the elite Red Shoulder Battalion of the Gilgamesh Confederation military during the Hundred Years War against the Balarant Union. He endured the unit's notoriously brutal training regimen under Yoran Pailsen's command.

Late in the war, Hagard and three others—Chirico Cuvie, Gregore Garosh, and Murza Melym—were selected for a covert mission to attack allied forces on the asteroid Lido due to their problematic histories with superiors. Hagard later revealed this mission was Pailsen's deliberate attempt to eliminate them.

After the war and the disbandment of the Red Shoulders, Hagard reunited with his former comrades. They shared grievances against Pailsen: Hagard had lost his right hand, requiring cybernetic replacement, while Garosh was shot multiple times and Melym discovered his family dead. Hagard concealed his cybernetic hand until Chirico exposed it during a confrontation.

Hagard participated in the assault on Pailsen's fortified compound in the irradiated Belaida Plains, piloting a customized Scopedog Turbo Custom-LRS. During the battle, he provided covering fire for Chirico and Garosh as they advanced. After Melym and Garosh were killed by the Perfect Soldier Ypsilon, Hagard arrived in his heavily damaged Scopedog as Pailsen prepared to execute Chirico. Hagard shot and killed Pailsen, achieving their revenge. He succumbed to his injuries moments later, dying in Chirico's arms.