Mega Monster Battle: A Journey of Destiny

[In this author's headcanon, Pitterites can have children + power levels may go off the rails + not an Ultraman universe]

In this universe, there is a race capable of controlling monsters, known as the Reionics. They are scattered across various planets. One defining trait of the Reionics is their ability to summon monsters using the devices in their hands, then fight other Reionics. Survival of the fittest is their law. To learn how they came to be, we must speak of the Ultimate Life Form, Alien Reiblood.

The Ultimate Life Form, Alien Reiblood, once ruled the entire universe for tens of thousands of years, wielding a power so great that evil aliens feared him. Although his physical body has long since perished, his spirit endures. By spreading Reiblood genes far and wide or possessing others, he seeks new heirs and a chance to reclaim his place as ruler of the universe. He is a vicious and terrifying alien. The Reiblood are warmongers who constantly control their Battle Nizers, using the monsters within them as weapons in brutal Reionics battles. The ultimate victor inherits Alien Reiblood's power and becomes ruler of the universe.

Of course, there are exceptions. One Reionics from Planet Pitter chose to flee rather than take part in this cruel slaughter.

Twenty years later, as the gears of fate begin to turn, she will have no choice but to face this cruel battle. But this time, she will not be the one fighting. It will be her child...