Taken From Wikipedia:

The story follows Justy Kaizard, a police officer who chases down criminal espers; his tactics might be similar to those of a bounty hunter but he is a salary-drawing officer. The lead character is also an esper, gifted with remarkable powers. He is able to moderate his psychic forces by the use of the headband that he wears. With this device, which acts only as a psychic damper, he can finely attenuate his powers to prevent collateral damage