One day, high school student Michio Kaga attempts to start a strange online game he found while browsing the internet. Instead, he gets transported to a rural village in the game's world, equipped with special skills and an overpowered sword. After collecting his thoughts, he finds himself battling against bandits and soon realizes that he cannot log out. Resigning himself to fate and accepting this reality, Michio sets out on a journey—enjoying his new life, conquering dungeons to earn money, and building a harem to satisfy all his manly desires.

Ken Usato, an ordinary high schooler, wishes for something fantastical to occur in his unremarkable life. Such an opportunity arrives when he is transported to another world alongside Kazuki Ryuusen and Suzune Inukami, two prodigious members of his school's student council. Arriving in Llinger Kingdom, the three are deemed to be the heroes tasked with stopping the impending invasion by the Demon Lord's army. However, this is a misunderstanding—Usato was summoned by accident and, unlike his two friends, is not one of the heroes. Despite this disheartening revelation, Usato learns that he has an aptitude for the extremely rare healing magic. This catches the attention of Rose, the intimidating captain of the kingdom's Rescue Team, who forcibly takes custody of Usato to mold him into a full-fledged healer. As he undergoes grueling training under Rose's supervision, Usato resolves to become capable enough to protect his friends from the dangers of this world.

Alto Goldfilled, a diligent student at the Ortigia Academy of Magic, aspires to become a powerful sorcerer. But he is unable to become one as, despite his excellent grades and strong commitment to his studies, he fails his summoning class. With the threat of repeating a year hanging over his head, Alto tries following an old, worn-out grimoire in a desperate attempt to resolve his situation. To his surprise, he succeeds and summons a powerful demon named Vermeil. As a sign of gratitude for releasing her, Vermeil agrees to become Alto's familiar, sealing their relationship with a deep kiss. Little does Alto know what else he is capable of and what Vermeil's past hides.

Ten years ago, at the peak of the VRMMO development industry, a game titled Kiwame Quest entered the scene with potential like no other. Boasting a colossal total of 10 sexdecillion branches of possible story scenarios, this game pursued ultimate realism, ranging from humanlike NPCs to the perfect replication of all senses and physical abilities. But it soon became apparent that the game was too realistic, and the popularity of VRMMOs in general gradually began to plunge. At present, due to an accident a few years prior, the high school student Hiroshi Yuuki now immerses himself in full-dive RPGs as a form of escapism. After failing to acquire the latest version of his favorite game, Hiroshi stumbles upon a game shop and meets its beautiful clerk Reona Kisaragi who convinces him to buy a copy of Kiwame Quest so that they can play together. The first time Hiroshi plays the game, he marvels at the realism it offers. However, his astonishment is short-lived as he sets off a series of misfortunes, quickly realizing that the game is even worse than his already stressful life. Nevertheless, Hiroshi still finds himself logging on again despite his growing contempt for the game. With no do-overs in his current disadvantageous situation, Hiroshi only has one goal—clearing the game!