The Four Cardinal Heroes are a group of ordinary men from modern-day Japan summoned to the kingdom of Melromarc to become its saviors. Melromarc is a country plagued by the Waves of Catastrophe that have repeatedly ravaged the land and brought disaster to its citizens for centuries. The four heroes are respectively bestowed a sword, spear, bow, and shield to vanquish these Waves. Naofumi Iwatani, an otaku, becomes cursed with the fate of being the "Shield Hero." Armed with only a measly shield, Naofumi is belittled and ridiculed by his fellow heroes and the kingdom's people due to his weak offensive capabilities and lackluster personality. When the heroes are provided with resources and comrades to train with, Naofumi sets out with the only person willing to train alongside him, Malty Melromarc. He is soon betrayed by her, however, and becomes falsely accused of taking advantage of her. Naofumi then becomes heavily discriminated against and hated by the people of Melromarc for something he didn't do. With a raging storm of hurt and mistrust in his heart, Naofumi begins his journey of strengthening himself and his reputation. Further along however, the difficulty of being on his own sets in, so Naofumi buys a demi-human slave on the verge of death named Raphtalia to accompany him on his travels. As the Waves approach the kingdom, Naofumi and Raphtalia must fight for the survival of the kingdom and protect the people of Melromarc from their ill-fated future.

For high schooler Kei—and for at least forty-six others—immortality comes as the nastiest surprise ever. Sadly for Kei, such a feat doesn't make him a superhero. In the eyes of both the general public and governments, he's a rare specimen who needs to be hunted down and handed over to scientists to be experimented on for life—a demi-human who must die a thousand deaths for the benefit of humanity.

After a disastrous romantic confession, Masamune Okumura finds solace in the fictional world of anime and manga. Now a second-year high school student and the president of the Manga Research Club, Masamune spends a peaceful existence watching the adventures of the angel Liliel, his favorite character. In the beginning of the academic year, Masamune’s life is turned upside down when he meets first-year student Ririsa Amano, a passionate cosplay practitioner. Despite Masamune's initial reluctance, the determined young woman manages to convince him to become her personal photographer for the production of a collection dedicated to their common favorite character: Liliel. As Masamune enthusiastically discovers the world of cosplay and photo editing, he is unexpectedly reunited with his childhood friend Mikari Tachibana, who has become a model in the hope of impressing her beloved upperclassman. Realizing that modeling is not enough to intrigue the hopeless otaku, Mikari decides to join the club and become a cosplayer herself, all to finally have a chance at winning Masamune's heart. However, Masamune's love for fictional characters may not be capable of extending to those who impersonate them.

Humanity and demonkind have been on bad terms for millennia, resulting in the continent of Leunders being split in two. Although the situation has stabilized between the races, the fragile peace breaks when the new demon king launches a fierce all-out attack. With all of the non-demon nations falling to the violence in under a year, humanity's hope rests in a special squad, led by swordsman Kyle Leonard, that must assassinate the demon king in order to bring an end to the war. During the dangerous mission, Kyle ends up in a clash with the demon king that brings him to the brink of death. As Kyle realizes he has lost everything he wanted to protect, a mysterious gem transports him back in time before the conflict even started! Now with knowledge of future events and a strong desire to save his loved ones, Kyle sets out to become even stronger to prevent the extinction of humanity.