
Somewhere in the universe, Planet H12, which closely resembles Earth, is suddenly attacked by space kaiju from another planet. As the planet collapses and faces extinction, one lone alien escapes to Earth. His name is "Teo", a the lonely alien who will eventually grow to become Ultraman. On Earth, he lives as Ibuki Mitsuishi, a third-year veterinary student at Meishin University. Although he struggles with the common sense of Earthlings, he leads a peaceful life communicating with the animals he loves. However, the same space kaiju that destroyed his home planet suddenly appears on Earth, bringing a crisis. When his strong desire to "protect" overcomes the fear in his heart, a brilliant light transforms Ibuki into a blue giant of light!

Ibuki Mitsuishi, a student at Meishin University's Department of Veterinary Medicine, is actually an alien. Having lost his home planet, he came to Earth all by himself. While enjoying peaceful days immersing himself in Earth's culture, a meteorite suddenly crashes down. Amidst the chaos of the panicked crowds, Ibuki's world is turned upside down once again!

After encountering the Mini Kaiju, Ibuki rushes around the university looking for a place to hide it. Meanwhile, Kyoko Shiga, an investigator from the mysterious organization UTTF, begins to take action against the kaiju threat and contacts Professor Minobe of Meishin University. Ibuki breathes a sigh of relief upon finally finding a hiding place for the Mini Kaiju—but his relief is short-lived as a welcome party for his joining of the Astronomy Club suddenly begins!?