In a certain world far far away from earth but similar to it, there lives evil entities called "monsters". Using the power from the Demon Lord's fragments, they strive to destroy their own world.

In order to stop them from doing so, Children who are gifted with the Hero's fragment are trained to kill these evil beings with their gifted abilities.

These children are trained in the best school of all, Reinevere High.

"My first day of school... I can't wait to make friends!"

That school is also where Haru Kobayashi will spend his high school years.

Will Haru be able to graduate peacefully?