Denji is a teenager who lives his life as a Devil Hunter.

Aiming to pay off the debt he inherited from his father, he starts hunting devils for the yakuza with his buddy Pochita, a "Chainsaw Devil", while living a tragically poor life.

Just when things seem like they couldn't get any worse, Denji gets betrayed and killed by the yakuza. As Denji starts passing out, he hears someone calling from inside his head...

After being taken into custody by Makima, one of the Public Safety Devil Hunters, Denji finds himself head over heels in love with her thanks to her suggestive insinuations.

Wishing to team up with Makima, Denji arrives at the Devil Hunters Headquarters in Tokyo, and gets introduced to Aki Hayakawa, a senior hunter that he was supposed to partner with. But then Hayakawa beats Denji up, and demands that he “quit this job”...

Aki Hayakawa, Denji, and Power start living together.

Denji finally fulfills his dream of touching Power’s boobs, but is shocked when things do not turn out the way he expected. As Denji realizes that chasing his dream was more fun than achieving it, Makima approaches him and says, "If you can kill the Gun Devil, I’ll grant you one wish.”

Sawatari sends the "Ghost Devil" after Hayakawa, and he's nearly killed before the "Ghost Devil" stops and hands him a cigarette with a message from Himeno. The words inside give Hayakawa the strength to kill the “Ghost Devil” and capture Sawatari.

Meanwhile, Denji heads into his rematch with Samurai Sword. With a pull of the starter on his chest, he transforms into Chainsaw Man.

And now, the last battle between Chainsaw Man and Samurai Sword has finally begun...