In another world, the Hero and the Demon Lord waged a great battle. As their powerful magics collided, the explosion crossed into other worlds and destroyed a classroom full of high school students. The victims who died in the explosion were reincarnated in that alternate world. But one girl, the one with the lowest standing in the class, was reincarnated as a spider. Nevertheless, she faces this challenge head on with great determination. This is the story of a weak spider monster, doing whatever it takes to survive.