Naofumi Iwatani, an uncharismatic otaku who spends his days on games and manga, suddenly finds himself summoned to a parallel universe! He discovers he is one of four heroes equipped with legendary weapons and tasked with saving the world from its prophesied destruction. As the Shield Hero, the weakest of the heroes, all is not as it seems. Naofumi is soon alone, penniless, and betrayed. With no one to turn to, and nowhere to run, he is left with only his shield. Now, Naofumi must rise to become the legendary Shield Hero and save the world!
After quitting his job at a toxic company, Shiro Amata moves into the house his grandmother left him in her will. There, he soon makes two life-changing discoveries: one, his grandmother was really a witch from another world, and two, said other world is just on the other side of her closet door! Thanks to a book she left for Shiro, he also manages to obtain an all-powerful skill called "Equivalent Exchange," which allows him to turn money from his world into otherworldly currency and vice versa.
With this, Shiro decides to set up shop and sell convenient items like matches to the colorful inhabitants of the other world. His plan: make a massive profit on the goods he brings from home to become so rich that he never needs another job ever again!