The huge "Academy City" located in western Tokyo. In this city with a total population of 2.3 million, of which about 80% are students, special courses for the development of superpowers are implemented, and students' abilities are evaluated in six stages from "no ability Level 0" to "superpower Level 5". In such an academy city, the strongest superpower user, Accelerator, who reigns at the top of the superpowers. He ranks first among the only seven "superpowers" with abilities far exceeding others, and because of this power, he lives a daily life full of killing. Repeated and unconventional "experiments", and the defeat tasted in the end of the pursuit of absolute power. After that, his fate changed dramatically with his encounter with a girl, the last order. The strongest and most vicious "evil" - Accelerator, sweeps away the "darkness" of the academy city!!