The DemiKids games serve as the inspiration for this series that tracks the intriguing adventures of childhood pals Jin, Akira, and Lena. The trio has always been deeply fascinated by the enigmatic. While unearthing the "Akuma Compendium" in the library with new transfer student Ami, they accidentally unleash demons by reciting an incantation. Ami enlightens Jin and Akira that they are Devil Children, seemingly fated to steer the world's destiny. Ami hands them Devil Risers before taking them through the "Door of Time," transporting them to Valhalla, an alternate world. In this realm, Imperius, a malevolent monarch with a lust for power, seeks to conquer the world. With the help of their friends Rand (a Sol Lion) and Gale (a Hylon), Jin and Akira confront Imperius and wage war against him.