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...

Denji and Tokyo Special Division 4 members enter a hotel to collect a piece of the Gun Devil. However, they end up being trapped on the 8th floor due to the devil’s extraordinary power.

With the members being cornered on the endless 8th floor with seemingly no way to escape, the devil makes them an offer: “If you let me eat Denji, I will let all of the other devil hunters leave in one piece.”

Samurai Sword's vicious attack resulted in many lost personnel for Public Safety Devil Extermination Division 4.

Aki Hayakawa wakes up in a hospital bed, unable to accept the reality of losing Himeno. Kurose and Tendo then appear in front of Hayakawa, letting him know that they are now in charge of coaching him.

Meanwhile, Makima introduces Denji and Power to a member of Public Safety who will act as their mentor in order to strengthen Division 4.