"You make us sound like petty thieves. Can't you at least say 'obtained' or something?"
- ―Jack to Shin, on a translator device for Red
NOTE: Due to there being several differences between the manga and anime adaptation, the History section has been split into two tabs.
Previously associated with an unknown organization, his real name is unknown but he currently goes by the name Jack. An information broker living with in the Alien City, Jack was the only human resident of the city somehow living a comfortable life, in fact Dan Moroboshi stated he refused to leave. Moroboshi was a regular customer of his regularly coming for information to help with his investigations. When he was first met by Shinjiro Hayata, he had just won a boxing match with an alien combatant, winning by Knockout showing his skills as a boxer but implying he may not be a normal human being.
After the match, Jack met Shinjiro and Moroboshi and discussed the cases with them, unfortunately he had no leads for them save one race of aliens and it was very unlikely they were the culprits. He also noted that the other string of murders was completely unrelated to the ones connected to Alien Adacic and his organization. Moroboshi also asked Jack if he had gained permission to use the bracelet he was wearing.
Afterwards, Moroboshi left the two in the recreational area as he went to see other information brokers. There Jack talked to Jiro, noting he seemed lost questioning if it was because of the city. Jack also noted that he knew Shin and said that he had helped him sometime in the past. Before he could finish they were interrupted by a large alien named Red. The former champion of the arena before Jack defeated him, he had come for a rematch. Jack implying to Shinjiro that he won through deceitful means set him up to take his place against Red noting that Shinjiro was 'Ultraman' to the boy's surprise. After Jiro was thrown away by Red's punch, Jack translated for the large alien noting its surprise that Jiro could still stand after that.
Sometime later, he and Red ran into an agent and contacted Moroboshi. Later they were paid by Edo to cause a commotion to test Shinjiro. Jack apologized to Shinjiro, before giving Red an unknown serum that caused him to grow into his true, giant form. After the two had fought, ending with Red's defeat, and Shinjiro's learning to fly, Jack congratulated him on winning.
Agent Adad met with Jack and Red at a restaurant, where they discussed the Star Cluster Council. Adad revealed that he had met with Bemular several nights before, before giving Jack a tip that he was aware of a terroristic plot to attack the alien city. The agent then left the pair.
During Shinjiro, Dan, and Seiji Hokuto's battle with the Ace Killer Squad, Jack and Red were the first of the reinforcements to arrive. Clad in battle armor and wielding a large repeating laser, Jack opened fire on the squad while Red transformed into his true form to do battle with Alien Woovelve. Jack later escorted the injured Moroboshi off the battlefield.
After the battle, Jack kidnapped Yapool and escaped to New York to prepare for future threats, leaving Red behind. He and Yapool worked on making new Ultraman Suits over the next few months, getting three ready by the time the Star of Darkness emerged in New York. Jack and two others, in their Ultraman suits, deployed when a riot started and managed to protect Rena Sayama from a group of thugs. They were joined by Red, Adad and Taro, but soon found themselves overwhelmed by the Golden Fortress. Fortunately, Moroboshi arrived with new weapons and single-handedly destoyed the giant robot, leaving them and the other Ultramen to fight against the Star of Darkness' members. Jack and Red teamed up on a brutish alien, but the foe proved too tough for them. Moroboshi arrived and simply sliced the alien in half, upsetting the both of them.
Jack was a human born and raised in the alien city, working as a wrestler in a gambling den. He also doubled as an informant to the SSSP.
After noticing a string of murders, the SSSP sends Dan Moroboshi and Shinjiro Hayata to find Jack, hoping that he would know what was going on. After his wrestling match, Jack tells Moroboshi and Shinjiro about the recent serial killings. Jack gets to know Shinjiro after Morobhoshi leaves, until Black King, Jack's opponent from earlier, arrives to cut off their conversation by strangling Shinjiro. Fortunately, Moroboshi returns and scares the beast off.
At the request of the SSSP, Jack set up Black King to fight Shinjiro in the city to force him to further develop his powers. After the deed is done and Shinjiro can now fly, he is thanked by Ide, who also apologizes. He also later helps the SSSP find Alien Igaru, identifying him as the one behind the serial killings. Jack was implied to gave been contacted by Seiji Hokuto to learn of Shinjiro's identity. He also planted or hacked into a camera in the subway to spy on Seiji, Shinjiro and Morboshi, but the camera was spotted and destroyed by the former. Agent Adad also meets up with Jack to tell him that he is looking for someone, a talented technician, but Jack does not want to help him.
In the midst of night, Jack infiltrates the SSSP via rooftop, knocks out Yapool and puts him in a bag.
- Age: 32 years old
- Height: 188 cm
- Weight: 116 kg
- Powers and Weapons
- Combat Prowess: Jack is clearly a grade above normal human fighters as he won a boxing match with rather large alien opponent. He won by knockout and with no visible injury.
- Information: Jack is an information broker and as such knows how to get information, particularly info that involves aliens and alien criminal activity.
- Alien Languages: Jack has knowledge of alien languages, as expected of a person living in the alien city. He demonstrated this with Red, translating his words for Shinjiro and even speaking back to him in his own language.
- Jack's voice actor, Keiji Fujiwara also voices Tony Stark/Iron Man in the Japanese dub of Marvel Cinematic Movies. Similarly, Tony and Shinjiro Hayata, the protagonist of the ULTRAMAN manga fight enemies with red-colored exosuits. Also, Iron Man's armor had been compared to the Ultraman Suit.
- His name is a distinct nod to Ultraman Jack.
- Another reference is the bracelet on his left wrist, a possible nod to the Ultra Bracelet Ultraman Jack wore. This bracelet seems important as Moroboshi commented that Jack needed someone's permission to use it.
- Due to his name, the fact that he defeated not just one alien but Red, it is suspected by some fans that he may have the Ultraman Factor.
- Jack was purposely designed to have resembled Hideki Go from back during the time of Return of Ultraman, what connection they actually have beyond that is unknown.