Jin was a hard working member of DEUS, with a loving girlfriend named Elea, who worked in the energy department of the government on Project Aqua. Jin noticed something wrong with the world and eventually came to the conclusion that some invisible force was controlling mankind. This was more apparent when members of the Project Aqua team were being disposed of following a great discovery. Seeking to protect his beloved and stop the invader's plans, Jin explained everything he knew to Elea and went with her to sabotage Project Aqua. Although they partially succeeded Jin was gunned down on a bridge over the lake designated for the experiment. He was shot by his fellow agents while protecting Elea and both fell into the lake. Unconscious and dying, Jin was unaware when Elea struck a deal with the entity from the other universe, giving it his body to save his life. Later that night he awoke in Elea's apartment, with no knowledge of who he was or his past. Elea was there, and as an unknown enemy was storming the building she gave him a pair of red glasses, a special bracer and threw him out the window. The bracer slowed down his decent to a safe speed, looking back he saw the apartment explode.
For some time Jin continued his work as a DEUS agent, fighting space invaders and befriending interstellar entities seeking peace, as well as seeing a fare share of tragedies. Using the red glasses Jin would call on the otherworldly power to fight the battle he and his human compatriots could not all the while maintaining his secret identity. Yet several times he met Elea who hinted at a greater destiny for him as well as having the feeling that he was being watched by some unseen power. Eventually his suspicions more or less proved to be true during an incident at the same lake, where he nearly lost his life. The news spoke of a meteor striking the lake and irradiating it along with a man who was caught in the accident. Having a sense of nostalgia about it, Jin proceeded to the lake and was shocked that there was no radiation and that the man, a journalist, was fine. Giving Jin a disc, he warned him of the government. Several workers appeared and gunned the man in cold blood, letting Jin go due to his DEUS status. Later Jin heard the news say that the man was alive and being treated for radiation poisoning, Jin knew the man's warning was correct.
Despite a scolding from his superior and a suspension, Jin continued to investigate, even convincing the reluctant S and K to assist him. The trio eventually made their way and found Elea's base, who explained all that Jin had previously told her about what was going on. The shadow rulers of the world were plotting to invade the other dimension via the Project Aqua gate created in the lake water. The four battled their way through DEUS agents and split into teams to take down two important facilities; Jin with Elea and K with S. Eventually Jin questioned Elea about his memories and his powers but she warned that the revelation of those things would be detrimental to him. Suddenly they were attacked by an unseen enemy and Elea was knocked out. Jin fired into the air eventually knocking out the monster's cloaking field. Drawing the glasses, Jin was struck by the image of a lake and a woman in white waiting by its edge. With no time to ponder the vision's meaning he transformed, placing Elea in a safe place went off to fight. Unfortunately he was set upon by three monsters, who wrapped him in energized thread and blasted away at him.
During this Jin was contacted by the hive mind of the invaders, represented by three people in a garden outside a small mansion. They explained their nature and motives, they had long ago invaded the Earth, taking control of mankind's information networks, they took over the world without anyone noticing. Though Jin accused them of being invaders, they excused themselves as being a natural part of the world, which man created with his information networks, which is why they felt their presence was needed on the world on the other side of the gate. Telling him his use was over he finished their conversation by calling him the name of the Red Giant, Ultraseven.
Jin's battered body was hoisted into the air and dropped, he transformed back defeated, and the glasses fading away. Elea rushed to his side and confessed what happened during their last visit to the lake and how the giant's mind was sealed away to preserve his. Suddenly light gathered around Jin's body, the glasses reformed and Jin awoke, however it was the giant's consciousness that spoke. Taking his true form he promised Elea to answer her prayer. Seven defeated the three giant monsters with ease, and a fourth that was hidden before tunneling into the earth and confronting the entire hive which he wiped out. He then proceeded to save S and K and brought them to Elea by the lake at sunrise. Separating from a now fully healed Jin, he was placed him in front of the group where Jin elaborated the identity of the giant, a savior from another world; Ultraseven. The group watched as he returned to his own world, having saved both, Seven aka Dan Moroboshi returned to greet the woman in white, Anne, who was waiting for him at the lake side in his world.
Ultra Eye: This device was given to him by Elea. Like Dan Moroboshi and Masaki Kazamori, Jin uses the Ultra Eye to transform into his Ultra form. Unlike the other two, Jin transformed in real time, forgoing the transformation scene. When he placed the glasses on his face, they shined and turned into red light that covered his body and turned him into Seven. The transformation is as fast as a flash of light. When he grows in size, the light will shot up with a swirl of red energy before revealing Ultraseven.
Powers and Weapons
- Training: Jin is a trained agent, even with out his memories he had excellent martial art skills, marksmanship, espionage tactics and computer know-how.
- Equipment: as an agent of DEUS, Jin has access to technology that may seem otherworldly
- Ultra Eye: Using the Ultra Eye, Jin can transform into the entity called the red giant (Ultraseven).
- Unlike most protagonists of an Ultra series, Jin is never shown flying any type of fighter plane.
- Jin appeared to be very intelligent, since he was the one who first detected the presence of the Shadow Rulers while the other DEUS agents and humanity in general were blind to their manipulations.
- Due to being unconscious and his lack of memories, Jin was the only Ultra host to not know the origins of his powers or that he had merged with another being until his separation from Seven.
- Jin's combat skills appear to be greater than that of most protagonists, in human form and during his battles as Seven his fights were won in record times, even for Ultraseven himself who was known for short battles. However, when Seven had control of their bodies he was shown to be more skilled than him taking down the Mecha Graykess that easily defeated him, although it may have been that Seven was aware of them while Jin was ambushed.