Guts, who will later be known as the Black Swordsman, is a young mercenary traveling from place to place, recognizable by the enormous greatsword he carries. He takes on jobs that pay the most, but never stays with any group for long—until he comes across the Band of the Falcon. After completing a job, Guts is ambushed and defeats many members of the band in combat. Griffith, the founder and leader of the Band of the Falcon, becomes interested in Guts and challenges him to a duel. Though the other members are no match for Guts, Griffith defeats him with a single blow.
Incapacitated and brought to the Band of the Falcon's camp to recover, Guts awakens two days later. He confronts Griffith, and they duel again, this time under a condition: if Guts loses, he must join the Band of the Falcon. Because of his still-healing injuries, Guts loses the fight and is inducted by Griffith.
Over the next three years, Guts rises to become one of the Band of the Falcon's commanders. On the battlefield, his combat skill is second only to Griffith's, as he takes on large groups of enemies by himself. With Guts' immense strength and Griffith's leadership, the Band of the Falcon dominate every battle they fight. But something sinister lurks in the shadows, threatening to change Guts' life forever.