Kazuma Satou is a reserved 16-year-old who loses his life in a tragic yet laughable accident. After his untimely death, Kazuma finds himself standing before Aqua—the self-proclaimed water goddess who presents him two with choices: to ascend to heaven or reincarnate in a real fantasy world. Picking the latter, Kazuma gets tasked with defeating the Demon King, an occurring threat in his new world. However, Aqua's provocative attitude strikes a nerve, and in the heat of the moment, Kazuma takes her along.

Kazuma and Aqua, now stuck together in another world, embark on a journey. They soon acquire two more companions: Megumin, an archwizard wielding devastating explosion magic; and Lalatina "Darkness" Dustiness Ford, a crusader with a worrisome case of masochism. The four of them form an odd party, each member contributing their unique share of power and a peculiar personality. Unfortunately, their adventure soon proves to be challenging and costly, Kazuma's new life may be nothing but a headache.