Introduction arc

Covering the first four chapters and the opening two episodes, this short arc kicks off the entire series with no predecessor, handing off to the Bat Devil arc. It introduces the core premise, the lead cast, and Denji's transformation into Chainsaw Man.

Denji crosses paths with the Chainsaw Devil Pochita and saves the wounded creature, and the two become inseparable partners taking on devil-hunting work to chip away at the debt Denji owes the Yakuza. During one job the Debt Collector, controlled by the Zombie Devil, lures and murders them both. To keep Denji alive, Pochita fuses into his body as a replacement heart, and Denji rises as Chainsaw Man to butcher the Zombie Devil and its undead minions.

Makima of the Public Safety Devil Hunters reaches the scene, recognizes how unusual Denji is, and recruits him into her squad. Brought to Tokyo, Denji is partnered with Aki Hayakawa, who initially tries to drive him out but ultimately lets the boy move in with him.

A third squad member soon joins them, the blood-loving fiend Power, and Denji is thrilled to learn his new colleague is a girl. The arc closes having set up the trio at the center of the saga. Characters introduced include Denji, Pochita, the Tomato Devil, the Debt Collector, the Zombie Devil, Makima, the Marshmallow Devil, the Muscle Devil, Aki Hayakawa, and Power.