Shigeo Kageyama is an average middle school boy, nicknamed Mob (モブ Mobu) (meaning "background character") for lacking a sense of presence. Although he looks like an inconspicuous person, he is in fact a powerful esper. As he grows older, Mob realizes that his psychic powers are strengthening and becoming more dangerous. To avoid his power getting out of control, he constantly lives a life under an emotional shackle. Mob wants to live a normal life just like the others, but a barrage of trouble keeps coming after him. With the suppressed emotions growing inside Mob little by little, his power threatens to break through its limits.