After fanatically playing the VRMMO World Fantasy Online for almost a year, the shut-in yet relatively affluent 15-year-old Yuna receives a bear costume from the game's administrators. The outfit, while somewhat embarrassing to wear, turns out to have overpowered stats and effects that make her character significantly more powerful. After accepting the bear equipment, she finds herself transported to another in-game world that prevents her from returning to reality. Confused and unable to log out, Yuna sets out to explore this new environment. She rescues a girl named Fina from wild wolves, who then guides her to the city of Crimonia. With her eccentric bear attire, however, Yuna stands out wherever she goes, and alongside her boosted fighting prowess, her reputation quickly rises—to the point that people give her the nickname Bloody Bear. Undeterred by this change in her life, Yuna decides to take on the role of an adventurer and fully enjoy herself in her new world.

The day is as normal as it can be in high school as the students peacefully go about their everyday activities until an unprecedented catastrophe strikes the school, killing every person in its wake. Guided by what seems to be a miracle, a handful of students are fortunate enough to be reincarnated into another world as nobles, princes, and other kinds of people with prestigious backgrounds. One girl, however, is not so lucky. Being reborn as a spider of the weakest kind, she immediately experiences the hardships of her dire situation. Even so, she must press on to survive the numerous threats that endanger her life. Discovering that her new world has a system like that of an RPG, she tries her best to hunt prey and defeat monsters to level up and evolve. As she gradually grows stronger, she hopes one day her efforts will be rewarded, and that she will be granted a better life.

Vampires are known to have many weaknesses that balance out their incredible power, but the vampire lord Draluc happens to be weak to pretty much anything. The vampire hunter Ronald receives a job to infiltrate the castle of the so-called Invincible Progenitor and rescue a woman's son from the monster within. But upon arriving, he is dumbfounded to discover that the vampire quickly turns to ash by something as trivial as a clap of his hands! Moreover, the child he was sent to save had merely wandered in to play the vampire lord's video games while he slept! In a disastrous turn of events, Draluc's castle is destroyed, and the fragile vampire decides to move in with the hunter who has only just defeated him. Ronald, Draluc, and the vampire's pet armadillo John form quite the eccentric team as they are forced to work together while fending off Ronald's violent editor, the lesser vampires plaguing the city, and even their fellow vampire hunters.

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!