Fifty years ago, Earth was saved by an interstellar giant of light called Ultraman, who then vanished. Shin Hayata, the human who hosted Ultraman, had no memory of his heroic actions. Now, Hayata's son Shinjirou possesses extraordinary strength and resilience far beyond normal humans. The SSSP, the organization that once aided Ultraman, reveals Hayata's past to him, prompting him to don a power suit again and resume his role as Ultraman.
One night, Shinjirou is attacked by an alien named Bemular and is saved by his father, who sustains severe injuries in the fight. As dangerous extraterrestrials threaten the city and Hayata is unable to act, the responsibility falls on Shinjirou to step up as the new protector. Teaming up with the SSSP as Ultraman's successor, Shinjirou struggles with the moral complexities of his mission and questions how far he is willing to go to protect humanity.
