Shigeo Kageyama is an average middle school-aged boy, nicknamed Mob. Although he looks like an inconspicuous person, he is in fact a powerful esper with immense psychic power. To keep from losing control of this power, he constantly lives a life under an emotional shackle. In order to help learn how to control his abilities, Mob works as an assistant to con-man Arataka Reigen, a self-proclaimed spirit medium. Mob wants to live a normal life just like those around him, but a barrage of trouble keeps coming after him. With his suppressed emotions growing inside Mob little by little, his power threatens to break through its limits as he eventually encounters other espers like the Claws.