In the year 3023 in a world where electricity was never discovered, the land become polluted and inhospitable, possibly by radiation from biological warfare attacks. In order to survive, the human population constructs massive walled cities,completely cut off from the outside world, and perhaps even other walled cities. Inside these cities, humans live in darkness, lit only by the glow of dim lights powered by team, but are able to engineer a type of plant that grows in darkness without the need for sunlight. Despite this, the walled cities are still rife with inequality, as the engineers at the top of the city who control access to the doors and transport system are able to dictate how others lives, relegating many to the lower and more compact slums.

Due to the amount of waste products and trash accumulated within these walled cities - and because humans are unable to leave, scientists create a biological matter capable of eating waste products.Rowena Steel, a studious wizard in training residing in the lower slums, focused on medicine and researching how to help her community find a better life outside of the slums.

However, even inside the walled cities, the humans are not safe. A plague erupts - either starting in the cities or following them from the outside world. The plague erupts through the lower areas of the walled city, slowly but surely infecting and killing off the human population. During this time, people plead to be allowed to leave the city, but all access to the Control Room is cut off, and the engineers at the top leave the rest of the populace to their fate.

In a desperate bid to find a way out and save the human population, Rowena finds a way to upload their consciousness into an Ally body. While her consciousness was being uploaded into the Ally, the connection was interrupted when being transported as a result of the Isekai. Thus, not all of Rowenas memories and personality completed the upload.