Vinland Saga (Manga) Wiki

Ten years ago, a strong warrior named Thors lost his life in a fight with Askeladd, a powerful and ruthless Viking. Having witnessed his demise, Thor’s son, Thorfinn, became consumed by hatred and vowed to exact revenge on his father’s killer in an honorable duel. Thorfinn was recruited onto Askeladd’s ship with nowhere to go and began working with the crew as they pillaged settlements and tricked naive armies. Now, the young boy spends his days honing his battle skills while carrying out Askeladd’s bidding to earn his reward for a duel with the vicious captain. But despite having failed in all his bouts with the man he despises so much, will the day ever come when Thorfinn can finally defeat Askeladd and lay his father’s memory to rest?

Source: Anime-Planet