One day, a man claiming to be a god suddenly hacks a certain school's intercoms, ordering all of its students to team up and prepare to be transported to another world. There, they will be given special skills in the hopes that they become that world's heroes and defeat the Demon King. The initial transfer is a success. However, Seiichi Hiiragi, who suffers from his classmates' constant bullying, is left behind as no one is willing to be his teammate. Nevertheless, the self-proclaimed god decides to send Seiichi to the parallel world and lets him join his peers. Unfortunately, this fateful ordeal causes Seiichi to arrive at a location deep in the forest, far not only from his schoolmates but from human civilization as well. Seiichi's miserable days only seem to continue to worsen when he discovers a strange fruit known as the "Fruit of Evolution"—which may be his first step toward a significantly better future.

Thanks to the Fruit of Evolution, Seiichi Hiiragi's amazing new life in another world allows him to meet dependable allies and create formidable spells. His abilities catch the attention of Barnabus Ablitt, the principal of the Barbador Academy of Magic, who invites Seiichi to become a teacher at the institution. Coincidentally, Seiichi's classmates from Earth are enrolled there, which will lead to an awkward reunion if he is to meet them. Behind the scenes, however, an enigmatic cult called The Great Devil Order devises a sinister scheme to resurrect their deity and sacrifice the students of Barbador to hasten the process. As Seiichi's power is second to none, it is up to him to protect not only his friends but also the entire world from the looming darkness.