Denji, burdened by his late father's debt, spends his days slaying devils with his pet Pochita to pay off the yakuza. He dreams of a simple life with food and a beautiful girlfriend, but after a betrayal by the yakuza, he is brutally killed. In a twist of fate, Pochita merges with Denji, granting him devil powers and transforming him into a hybrid with chainsaw abilities. The Public Safety Bureau's Makima recruits him as a devil hunter, offering him a chance at a better life. Driven by his desires, Denji fights fiercely to make his naive dreams a reality.