Ultraseven (ウルトラセブン Urutorasebun), codenamed Agent 340, and sometimes spelled Ultra Seven, Ultra-7 or just Seven (when being referred to by the other Ultras, including his son), is the protagonist in the Ultra Seven TV Series. He is the third Ultra being to come to Planet Earth (first and only in the spin-offs).
Seven was sent to make a map of the Milky Way, he visits a planet that captivates him, Earth. On his visit, saves the life of a young mountain climber named Jiro Satsuma, who nearly fell to his death to save a fellow climber from sharing his fate. Instead of combining with him, like Ultraman did to Science Patrol member Hayata, 340 makes himself into an exact likeness of the unconscious Jiro (with more casual civvies), but renames himself “Dan Moroboshi” (モロボシ・ダン Moroboshi Dan) to avoid confusion. A mysterious but friendly and helpful young man, Dan joins the Ultra Garrison as its sixth member, but unbeknownst to them (and anyone else for that matter), and saves the day from alien invasions in his true form as Agent 340, christened by the Garrison as its “honorary 7th member”. He transforms by putting on the Ultra Eye.
He appeared as the main character of Ultraseven and the human form of Ultraseven. His codename to the Space Garrison was "Agent 340" but was christened Ultra Seven by the humans. Each member of the Ultra Garrison was codenamed Ultra One to Six, with Dan being the sixth member his true form was seen as an unofficial Seventh member of the team. Dan hails from the Land of Light in the Nebula M78, the same planet as Ultraman. Originally sent to map the Milky Way, he visits Earth and it captivates him. On his first day, he saves the life of a young mountain climber named Jiro Satsuma, who nearly falls to his death while saving a fellow climber. Instead of merging with him, as Ultraman did with Science Patrolman Shin Hayata, 340 morphs himself into a duplicate of the unconscious Jiro. However, he names himself Dan Moroboshi to avoid confusion.
A kind and cheerful young man, Dan assisted the Ultra Garrison in finding a way to detect Alien Cool's invisible ships, earning his place in the Ultra Garrison, since then he has fought for the Earth and its people at times facing moral dilemas, as at times he is left pondering the morality of his actions, such as when the Ultra Garrison destroyed an underwater city seemingly inhabited by the Earth's original inhabitants that humanity force underwater, simply because it was deduced as the origin point of a monster they had faced. Eventually Dan noticed that his Ultra Powers were fading, this was coinciding with his injuries pilling up. It is then that his mentor and superior appeared to him telling him that he needed to return to the Land of Light to heal. When he refused his superior placed a mental lock in Dan's mind preventing him from using the Ultra Eye. When facing the Goth Aliens and Pandon, Dan found a way around that block to save his friends. Though he saved his friends saved the one the aliens took, Seven was trounced by the Goth monster and barely defeated it. Back in human form Dan was found bleeding and heavily injured and taken back to the base for medical treatment. In his coma Dan was again visited by his superior who demanded that he return home and again he refused earning him his superior's ire. Upon awaking Dan snuck out of the base and traveled seeing on the news that Goth Aliens had attacked every major city on the planet. Heading to an abandoned where house Dan attempted to transform again despite a final warning from his superior, it was then that Yuri arrived, having been worried for Dan's safety. It was then that the revealed their secrets, Dan his true nature and origins and Yuri, her feelings for Dan. Transforming one last time Seven rescued to kidnapped team member and destroyed the Aliens and their base. However he still had to deal with a now cyborg Pandon. Barely holding his own Seven was saved by the assistance of his human allies allowing him to decapitate the Goth monster. His battle finished and the sun rising, Seven flew of to his homeworld knowing the Earth would be safe.