Denji harbors a simple dream: to live a happy, peaceful life and spend time with a girl he likes. Reality, however, is far removed from this wish, as Denji is coerced by the yakuza into killing devils to repay his crushing debts. Using his pet devil, Pochita, as a weapon, he is prepared to do anything for a little cash. Unfortunately, having outlived his usefulness, he is murdered by a devil contracted to the yakuza. Yet, in an unexpected twist, Pochita merges with Denji's corpse, granting him the powers of a chainsaw devil. Now capable of transforming parts of his body into chainsaws, the revived Denji employs his new abilities to swiftly and brutally dispatch his foes. Attracting the attention of official devil hunters who arrive at the scene, he is offered a position at the Public Safety Bureau as one of them. Now equipped with the means to confront even the toughest enemies, Denji will stop at nothing to realize his simple teenage dreams.