Abruptly catapulted into a fantasy world, Mimori Touka and his classmates have been summoned by the world's resident goddess to serve as heroes. Luckily, most of the students display amazing skills upon arrival—except for Mimori, whose abilities bottom out at a measly E-rank. With no further use for him, the goddess banishes Mimori to a dungeon from which no one has ever returned alive. Yet, as it turns out, Mimori's skills aren't so much worthless as they are abnormal. Abnormally powerful, even. If Mimori can only claw his way back to the surface, nothing will stand in his way from getting revenge.