Several years ago, a certain research facility conceived of artificially creating psychics in order to weaponize psychic powers. The project was named "Project PX." After countless sacrifices and atrocities, the first artificial psychic, PX-01, was completed.

However, the research facility was completely obliterated by the test subject PX-01. There were no survivors, and all data was lost. After the incident, the government learned of the unethical nature of Project PX and erased the project itself from existence.

Incidentally, her name is Mai. She is, ostensibly, a justice-loving esper girl. What you does not know is that she is the very girl once called PX-01.