Humans and Scub Coral (intelligent coral-like lifeforms) have been in conflict on Earth. The Scub Coral created Eureka, a humanoid Coralian, to help bring the two races together. Eureka becomes a combatant in the U.N.’s Acid unit and is ordered to protect a girl named Iris who has the ability to control scub coral. With the world in crisis, Eureka must find a way to protect Iris and the world.