Esper

A Power User, ESPer, Psychic or Ability User (能力者) is a person who has gone through the Power Curriculum Program and is theoretically capable of displaying a psychic ability; these individuals are given ratings of Level 0 through Level 5 by Academy City in an attempt to rank how powerful their ability is. However, not all those who have gone through the program are capable of even attaining an ability, and is ranked as a Level 0 by default.

Once a person becomes a power user they unconsciously emit an invisible energy field known as AIM, and are then incapable of using magic without inflicting harm to oneself.