I don't know how many years of vicissitudes and changes it took for the Land of Light to become so prosperous. Ultraman is known as the heroes who are the protectors of the universe, as well as the pioneers of the field of Japanese special effects drama.
There are parallel universes in which Ultraman is seen, and in the Heisei period of "Deja Ultraman," the hero of the Showa system, Hatsuneo Ultraman, appeared in the show, and their friendly handshake established the fusion of the two eras and through the two eras, and in the show, Daiko traveled through space and time in order to track down the monsters and came to the other parallel world, where he not only met the theater where the Ultraman was filmed by Roundtree but also had a great battle with the monsters. He was at a disadvantage in the battle with the monster, but fortunately, the first generation of Ultraman arrived in time, and the two of them teamed up to defeat the monster.
This shows that the Heisei Ultraman and the Showa Ultraman were characters from two different worlds. So the question is, why did Ultraman have to protect Earth from the monsters?
Deja, Dinah, Gaia, and Aguju are all Earth-born and bred Ultramen, so it's understandable that they would help Earth resist the invasion, but why would the Showa Ultramen be willing to help Earth resist the invasion as well?
We can easily see within the movie "Super Galactic Duel" that the Land of Light was also a galaxy with life many years ago, where there was prosperity and no wars, and they were also humans, just like the Earthlings.
But the star that gave the Land of Light its light eventually burned out because of its energy directly causing the Land of Light to fall into eternal darkness, surviving in a dark world, the inhabitants of the Land of Light, in order to make the world bright again, they organized a scientific research team, and the team ultimately invented the Plasma Spark Tower referred to as the Artificial Sun after a difficult research, and the Plasma Spark Tower will never go out, and the Plasma Spark Tower will never go out, and the Plasma Spark Tower will never go out. It can make the Land of Light exist in eternal light.
But the Plasma Spark Tower is not omnipotent, although it can make the Land of Light full of light, but its side effects are also unexpected, the powerful radiation has changed the inhabitants of the Land of Light in the body of the genes, their bodies began to grow larger, do not need to eat food, only need light to replenish physical strength, to maintain their basic life characteristics. They possessed great strength and athletic bodies, and they were the Giant of Light, Ultraman.
It turns out that the predecessor of Ultraman was a human being, very similar to the characteristics of the human beings on Earth, but the Earth because of the backwardness of technology, and rich capital management, countless monsters in order to plunder the capital management and come from the outer planets, and launched an attack on the Earth.
This originally had nothing to do with the Kingdom of Light, but the Light's Ultramarines couldn't bear to see such a blue planet being ruled by monsters, and since the Earth's humans are of the same race as themselves, the Ultramarines came to Earth to help the Earthlings defeat the invading monsters.
Secondly, the Kingdom of Light because it is too powerful, since the Ampera alien led the monster army invasion, has been 30,000 years no one dares to make trouble in the Kingdom of Light, during the period of time, although Belial returned to the Kingdom of Light to start their own revenge plan, but encountered the new generation of Ultraman Sailor, and ultimately lost.
And the Universe Police also need fresh blood, although countless Ultraman warriors insist on training in the Universe Police, but they have not seen real war, so they know nothing about the so-called combat experience, and the father of the Ultraman thought of a perfect way to send the Ultraman warriors to the Earth, which will not only ensure the safety of their own kind, but also can start a real battle with the monsters, it's the best of both worlds!
This is why the Ultramen of the Kingdom of Light came to Earth to help the people of Earth resist the invasion of monsters. In fact, the Kingdom of Light is always guarding the universe, and Earth is just one of the countless planets with life.