Impressed by the sacrifices of Seiji Hokuto and Yuko Minami by protecting the people during an attack of Verokron who was created by Dimension Man Yapool, the 5 Ultra Brothers gave the two humans lives, and send their new member Ultraman Ace to be their human host to fight off a age of new Monsters know as Choju.
An enormous silver-colored egg is found at a construction site. With curiosity getting the best of him, a worker is absorbed into the huge egg shortly before it submerges below ground. TAC investigates, but finds no traces of the construction worker, or the egg.
On patrol, Minami witnesses the sky crack open and a monster emerges. Destroying a bridge with a little boy on it, a passenger plane flies overhead and it, too, is destroyed. TAC investigates the wreckage and finds no sign of the little boy, nor the monster Minami described.
TAC agent Mikawa visits Mushitaro Kuri, an old acquaintance from middle school, who shows her a drawing he made of the terrible-monster, Garan. At the same time, TAC investigates a recently discovered fish that is millions of years old and resembles the drawing that Kuri made.
Two women go missing, with witnesses testifying that they vanished underground. The only common link between the incidents was that both women had type O blood.
An astronaut named Koyama returns to Earth to his wife and son, but is waylaid by Yapool and his latest creation, Brocken.
The mysterious star Goran approaches Earth, threatening to wipe out all life.
In a four-way fight between titans, Ultraman Ace is overpowered by Muruchi II, Doragory, and Metron.
A strange photographer named Junko shows up while TAC members ambush a terrible-monster, claiming to have been tipped off by Seiji.