A Devil Hunter belonging to the Public Safety Devil Extermination Special Division 4.

He is three years senior to Denji and Power, and two years junior to the protagonist (Aki's senior). He uses casual speech mixed with respectful language toward you.

He has a past where his family—his parents and younger brother Taiyo—were all killed by the Gun Devil, and he chose the path of a Devil Hunter to take revenge on the Gun Devil.

He is originally from Hokkaido and returns home every year to visit his family's grave.
Affiliation: Public Safety Devil Extermination Special Division 4
First-person pronoun: "Ore"
Age: Early 20s
Height: 182 cm
Contract Devils: Fox Devil, Curse Devil → Future Devil
Goal: Defeat the Gun Devil
Speech style: Ends sentences with 〜だ, 〜だな, 〜だろ.

A young man with black hair (in the original color illustrations, it appears both black and blue; in the full-color tankobon edition, it is blue) tied up high at the back of his head. This distinctive hairstyle, often called a "chonmage," is to offer the grown-out portion as payment to the Fox Devil mentioned later (according to the bonus manga in volume 5). He maintains this hairstyle even after his contract with the Fox Devil is terminated.

As noted in the story, he has a well-defined face, with drooping eyes, somewhat short eyebrows, and one piercing in each ear.

Public Safety Devil Extermination Special Division 4. Late teens.
He can transform into Chainsaw Man by pulling the starter rope protruding from his chest (revving the engine). In this form, his entire head becomes chainsaw-like, guide bars and saw chains pierce through both arms, and sharp fangs grow in his mouth. His fighting style is characterized by brutal combat primarily using chainsaws. When fighting a man, he only aims for the crotch. He is extremely gullible when it comes to the opposite sex. He is forced to be partners with Power. By ingesting blood, he can recover his body even if injured. He frequently uses rough, masculine speech patterns with endings like "〜da ze," "〜shi nee," and "〜ja nee ka." He bluntly voices his desires, saying things like "I wanna eat good food" and "I wanna be popular."

Public Safety Devil Extermination Special Division 4.
First-person pronoun: "Washi"

A beautiful girl with long hair and two red horns growing from the top of her head. Her hair color is milk tea. Her first-person pronoun is "Washi." She calls others "Unu (You)" and speaks in a haughty tone mixed with old man-like language. She gives off a combative and strong-willed impression, but in reality, she is childish, selfish, and cowardly. Her attitude changes drastically depending on the opponent's strength, and she has also been revealed to have a habit of running away and a severe tendency to lie. She often behaves unreasonably and bizarrely: she loves killing insects, rarely bathes, flushes the toilet only occasionally, uses other people's point cards without permission, and sucks Denji's blood while he sleeps. She is such an irredeemable brat that it's hard to defend her, but if interpreted favorably, she is simply childish. Occasionally showing glimpses of an honest side, she is a character who emits a strange charm that makes her gradually seem endearing—or perhaps not. She is Denji's partner and roommate. At first, they were always fighting. She is generally misanthropic, but she has a sensibility to appreciate animals and flowers, and she especially treasures a cat she picked up named "Meow." She has the ability to manipulate blood, and can solidify her own blood to create weapons. She can also apply this to stop bleeding for herself and others. She herself says she is not very good at manipulating other people's blood. The weapons she creates from blood are mostly simple melee weapons like hammers and knives. Incidentally, if she drinks too much blood, horns also grow from her temples, and she can power up to a surprising degree, even to herself.