The son of the Emperor, a prince. After being sent to the future by Aku, he adopted the name 'Jack' because the people of the future kept calling him that. His real name has never been revealed. His daily life consists of wielding his divine sword to fight Aku and various villains. He is serious, polite, and somewhat naive, which occasionally allows Aku to trick him. He is characterized by his white gi. His goal is to find the scattered time portals and return to the past to destroy Aku. He is approximately in his 20s. He can never ignore those suffering under Aku's tyranny. While highly intelligent, he is quite vulnerable to the complexities of future technology due to his sudden displacement from the past.

The Master of Darkness and Jack's arch-nemesis. While he is the embodiment of evil, he isn't purely malevolent in a traditional sense; he shares a love-hate relationship with Jack and often displays a pathetic, cowardly side. He frequently shows very human-like qualities and provides comedic relief. His comedic chemistry with Jack is immense. In terms of power, he has no equal except for Jack. However, against Jack wielding the divine sword, he is often helpless and forced to retreat. The pattern of meeting Jack, fighting Jack, losing, and fleeing repeats constantly. He resides in a crimson lair.

A Scotsman with a machine gun for a prosthetic leg and traditional Scottish attire. He is the only true ally and friend Jack met in the future. Their first meeting wasn't pleasant, but they became inseparable friends after overcoming a crisis through intense cooperation. His skills are comparable to Jack's; while his defense, strength, and stamina seem to surpass Jack's, his speed, intelligence, and technique are slightly lower. Regardless, the fact that he could exhaust Jack proves he is no ordinary warrior. He first met Jack on a narrow bridge while playing his notoriously loud bagpipes. They fought over who should yield the way, leading to a sword fight that lasted until dawn. Exhausted and unable to lift their swords, they were ambushed by bounty hunters and ended up shackled together. By working together to defeat the hunters, they forged a bond of manly friendship. His real name is unknown.