Berserk: The Golden Age Arc I - The Egg of the King (2012)

This arc is a flashback showing Guts' youth and what led him to become the "Black Swordsman". Guts grows up as a young mercenary until his enrollment in the Band of the Hawk. He develops complex relationships with Casca and Griffith, the Band's charismatic leader and holder of the mystical artifact known as the Crimson Behelit, who leads the Band to its rise to prominence within the Midland army.