Half a century ago, an extraterrestrial giant of light called Ultraman saved the Earth but disappeared. Ultraman's human host, Shin Hayata, was left with no memory of his time as a hero. Hayata's young son, Shinjirou, is discovered to have been born with a body more powerful and durable than that of any normal human. The organization that aided Ultraman, the SSSP, reveals Hayata's past to him. His father then dons a power suit again, assuming the role of Ultraman once more. One night, Shinjirou is attacked by an alien named Bemular and rescued by his father, who is severely injured in the battle. With dangerous aliens lurking in the city and Hayata out of commission, it falls to Shinjirou to pick up the torch. But in working with the SSSP as the new Ultraman, Shinjirou finds himself wondering how far he is willing to go to help people.