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”...

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.

A fierce battle unfolds between Denji and the menacing Samurai Sword. But even after Denji takes one of Samurai Sword's companions hostage, Samurai Sword slashes through them both until Denji is captured. Meanwhile, after seemingly being killed, Makima turns out to be alive. She sets out to rescue Denji with the help of Public Safety Devil Hunters from Kyoto, Kurose and Tendo.