* This is why in ''[[SamuraSamurai Jack]]'', the [[Big Bad]] Aku wants to keep Jack from returning to the past. Jack is an experienced samurai well-versed in demonslaying and defending the innocent. He thus is a viable threat, since his sword is the only weapon that can kill Aku. {{spoiler|The series finale showed that when Jack finally returned to the past, after fifty long years of unwanted eternal youth, it wasn't a fight so much as a one-hit KO as the younger Aku didn't bother attacking, only running for his life}}.