Samurai Jack: The Premiere Movie

In the distant past, an evil shape-shifter named Aku has brought destruction upon the land. As the citizens' last hope, a youngster is sent away to train as a samurai warrior. But when he returns as an adult to confront Aku, the warrior finds himself flung into the future through a time portal, landing in an unknown time and place. There, the locals dub him "Jack" and help him in his quest to return to the past and undo the evil brought by Aku.