The year is 3023.
Having lost nearly everything to war, environmental collapse, and rampant disease,

humanity establishes a new home underground, far from the contaminated surface.
As the surface becomes increasingly toxic, discussions arise around how to efficiently travel between underground settlements.
Digging tunnels proves to be astronomically costly and time-consuming,

prompting the need for a new surface-based transportation method that minimizes

contact with polluted soil and air.
Under the leadership of the underground nation "Overnation,"

the development of a new personal transportation device called

the "Teleporter" begins — a system designed to hover above ground, offering a far cheaper alternative to excavation or flight.

The Teleporter is a device that opens a rift in space, allowing instant travel to a chosen destination.
However, the technology has a critical flaw: if the arrival point is not vacant,

the rift cannot be fully stabilized, putting the user’s life in grave danger.
To resolve this issue, a series of secret animal-based safety tests—

known as "Foreign Matter Experiments"—are conducted in underground laboratories.
During one such experiment, a malfunction causes a high-performance

CPU to become embedded in a rabbit’s brain.

Empowered by its newfound intelligence, the rabbit turns on the humans who tormented it, seeking revenge.
To this terrifying creature, humanity gave a name: Telebbit.