Long ago in a distant land, I, Aku, the shape-shifting Master of Darkness, unleashed an unspeakable evil! But a foolish Samurai warrior wielding a magic sword stepped forth to oppose me. Before the final blow was struck, I tore open a portal in time and flung him into the future, where my evil is law! Now the fool seeks to return to the past, and undo the future that is Aku! This quotation begins each episode of Samurai Jack, which tells the story of a young prince (Jack) from Feudal Japan whose father's empire is destroyed by the demon Aku. The child Jack escapes destruction and travels the world training his mind and his body for years until he reaches adulthood, becoming a legendary samurai. Then, taking his father's magic katana, he challenges Aku to a duel and defeats the demon. However, before Jack can deal the killing blow, Aku creates a time portal and sends his opponent into the distant future, anticipating that he would be able to amass sufficient power to deal with the Samurai later. The protagonist arrives in a hostile, futuristic Earth ruled by Aku and filled with his robot minions and a large number of alien immigrant races of various appearances. The first people he encounters in the future call him "Jack" as a form of slang, which he adopts as his name - his true given name is never mentioned in the series.