A world where the Hero and the King of Demons wage an endless fight against each other. Powerful magic they used shattered the boundary between worlds and exploded in one of the school classrooms. Students caught in that blast were reborn in another world. The main heroine, who had the worst reputation at school, was reborn as a spider. Nevertheless, she managed to quickly come to terms with her new state. This is the story of one who, becoming a spider, does everything possible to survive.