When Aku is reborn to set forth his reign of terror, the Emperor's son is sent off to learn the ways of the samurai. That boy becomes a man and attempts to slay Aku with a mighty sword, but Aku banishes him to the future.
When Jack mistakenly destroys a group of scientists' chance to escape Aku, he and the scientists join forces to try and fix the problem, hopefully returning Jack home as well.