Along with his entire class, Touka Mimori was summoned to another world by the Goddess Vicius. While most were ranked quite powerful, Touka was the weakest among them, so it was only natural that he be disposed of. Vicius' first impression as a generous and loving woman soon gives way to her true, cruel nature, and she rallies his classmates against him, casting him into a cavernous labyrinth of death and despair.

Despite being the weakest, even he has a personal skill: Abnormal State Skill. This ability, combined with his low level "poison" and "paralyze" powers, proves to be a deadly medley—hindering the movement of monsters, then letting poison whittle away at their health until they die without having a chance to fight back.

Gaining new abilities and companions along the way, Touka aims to exact revenge on that spiteful goddess who cast him into this hellscape.