After a soccer game one day, six kids are playing a cute RPG-looking video game at their homes. One of them scored the winning goal, one was the goal keeper who barely missed the ball, and the others were two groups of two who were rooting for their respective sides. Suddenly, when they defeat a boss, a strange thing pops up in front of them, and they're sucked into the game world! Tomoru (scorer), Mio, and Dai end up together with Professor Galileo, who tells them that he's the one that created this game that they`ve appeared in, called Eureka, but he inadvertently got sucked into it as well. In order to get back to their world, they need to clear missions that pop up in certain areas of the world. So when a mission appears, Tomoru and the gang make the professor take them along.