On an Earth where neither heroes nor kaiju exist, an alien suddenly falls from the sky. This Ultra’s symbol is the red space boomerang he holds, the Omega Slugger, and his name means “ultimate.” “Omega” is an alien who has lost his memories. Taking human form and adopting the name “Sorato”, he becomes interested in the life forms called “Earthlings” that he is encountering for the first time and attempts to understand them. When a giant life form appears, amnesiac Sorato recalls a word—“kaiju”. As these kaiju continue to appear before him, a sense of duty awakens in Sorato’s subconscious. He transforms into “Ultraman Omega” and an intense, fast-paced fight unfolds. The Earthlings, in turn, are grappling with encountering these gigantic life forms and the alien that fights with a red slugger for the first time, watching from various places and trying to understand what they are. Before long, Sorato and an ordinary young man—an alien and an Earthling, become friends.