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...

Aki gets stabbed by Kobeni while protecting Denji. Seeing this, Denji jumps inside the “Eternity Devil” and starts attacking it. He fails to kill the “Eternity Devil” and his chainsaw power ends up fading after losing too much blood. But then, he manages to restore his power after eating the devil’s flesh and drinking its blood, and begins to fight back.

As Himeno watches Denji, she remembers the saying, “The Devil Hunters that devils fear are the ones with a few screws loose...”

Denji experiences his first, yet devastating, kiss.

An intoxicated Denji is taken to Himeno's house, where she starts seducing him. Feeling torn between Makima, whom he admires, and Himeno, who is standing in front of him, he decides to fall into temptation. However, Denji then finds something in his pocket: The Chupa Chups lollipop that Makima gave him.