Berserk

Berserk is a long-running manga series written by Kentaro Miura in 1990 which is set in a medieval Europe-inspired fantasy world. The story centers around Guts, a mercenary with a very large sword and a dark past, Casca , his ill-fated lover and Griffith, Guts's former best friend, who betrayed him in order to become a powerful god-like demon. The manga was adapted into a 25-episode anime series which covers Guts's origins with Griffith and Casca while they were members of a mercenary group called The Band of the Hawk. When Guts and Griffith's luck finally turns, the Band of the Hawk arc ends messily, and the series returns to the present day to show the deep-rooted effects of everything that happened in the previous arc. The manga is a masterpiece in terms of storytelling and artwork with well-developed characters and an interesting fantasy setting. Think of it as a manga equivalent of "A Song of Ice and Fire".