The Royal Diana Academy is a prestigious school that accepts individuals with adept magical abilities. Upon graduation, these students find themselves at the top of their field or employed by the royal family. Spica Virgo dreams of studying at the academy, aiming to be a top-rate sorceress like her idol Claude Sirius. Claude is a world-renowned sorcerer who became the institution's youngest instructor, but mysteriously disappeared soon after. Lacking the experience and connections required for admission, Spica finds herself unable to make meaningful progress with her training. One day, however, she meets a talking black cat with magical abilities. Hoping to change the situation for the better, she begs the animal to take her as his apprentice and teach her the magic she needs to attend the academy. The cat accepts the deal on one condition—she must find a way to reverse his feline curse. Despite the arduous challenges ahead of her, Spica is determined to prove herself as a student worthy of the cat's mentorship.

After achieving fruitful results in New World Online's previous events, the now famous Maple Tree guild is excited to explore the new floors introduced in game. As if their guild was not already feared enough, each member is motivated to find stronger skills for themselves in order to greatly expand their options in future battles. Not forgetting the importance of networking, the guild also forges amicable relationships with other notable guilds, such as the Kingdom of the Flame Emperor and the Congregation of the Holy Swords. With their eccentric guild master Maple at the forefront, the members of Maple Tree continue to stumble upon creative ways to implement their skills, driving the game developers crazy along the way.

After an enthusiastic invitation from her friend, Kaede Honjou reluctantly agrees to try New World Online: a very popular VRMMO played by thousands of people across Japan. Naming her in-game character Maple, she sets out on her journey. As a complete novice to such games, she allocates all of her stat points into vitality, desiring to not get hurt. With not a single point in any other stat, Maple has extraordinarily high defense, but she can't move quickly or hit hard. This does not end badly for her, however. Due to her high defense, Maple acquires overpowered skills such as Total Defense, Poison Immunity, and Devour. These skills, along with the incredibly powerful items she obtains, allow her to obliterate most enemies in a single hit. After only a few days of playing the game, Maple claims third place in a server-wide event, gaining a reputation as a player who is both unkillable and absurdly powerful. Despite her overpowered character, Kaede has much to learn. As she progresses through the game, she meets new friends and acquaintances, helping her complete new levels and events. Through all of her adventures, she may even pick up some other crazy skills that exceed all expectations.

In the year 1923, a vampire crisis takes Tokyo by storm. Provoked by the illegal trade of Ascra, an artificial blood source, the population of vampires begins to rapidly increase within the city. Under orders from Lieutenant General Sounosuke Nakajima, the Special Forces Unit 16 gathers vampires within the military to create a new undercover vampire-hunting unit known as Code Zero. Leading the unit is Colonel Yoshinobu Maeda. Responsible for locating the source of the Ascra trade as well as capturing and killing vampires, he is pressured into producing fruitful results amidst the growing criticism that threatens to decommission the unit. To make matters worse, the vampires within the unit are struggling to grasp their newfound powers and identities now that they are no longer human. With the world at odds against them, the members of Code Zero must find a way to curb the crisis or otherwise fall victim to their own demonic natures.