College student Iwatani Naofumi is reading a book titled "The Records of the Four Cardinal Weapons" in the library when he is suddenly summoned to another world and told he has to save the world as the Shield Hero, one of the Four Cardinal Heroes. And one morning, he finds all his money and equipment gone.

After refusing to hear Melty out, Naofumi switches to planning for the next Wave. When a bunch of young soldiers ask to join his party, he agrees, but on a certain condition. At the same time, he also tries to upgrade Raphtalia's class after she hits the level cap, but all he receives is harassment.

After being unable to for so long, Naofumi finally gets to upgrade his party's classes. He then takes part in a meeting of the Four Cardinal Heroes, held under the guise of a celebratory banquet. There, he learns of the existence of a bonus stage, with increased XP earnings. Meanwhile, Raphtalia gets into a fight at the party.