Denji

Denji is a tough fighter with a keen sense of danger. His rough nature hides a cunning mind that can find unexpected solutions in battles with demons.
Hand-to-Hand Combat: Even without his transformation, Denji remains a capable unarmed and armed combatant. Against a Leech Demon that was many times his size and weight, he was able to easily block its strikes while punching and headbutting it with enough force to damage it. His skills improved further after training with Kishibe, during which he learned to rely more on strategy rather than blind force.

Chainsaw Man Transformation: By pulling the starter coming out of his chest, Denji can transform into the bloodthirsty Chainsaw Man. Denji needs blood to use his powers, so if he lacks it he cannot fully transform, he can still manifest chainsaws, but they are much shorter and weaker. After going into full demon mode and returning to himself, his arms in this hybrid form appear to have transformed into a more mechanical construct, as opposed to the more humanoid appearance before his transformation.
Enhanced Strength: Denji has enough strength to catch a thrown car in midair without staggering, and throw it back with equal force. He was able to throw his own heart with enough force to pass through the Earth's atmosphere without getting lost in space.
Chainsaw Manifestation: As part of his transformation, Denji grows fully functional chainsaws from his arms, legs, and head. These chainsaws are extremely effective at cutting through demons, being able to cut through the Bat Demon's arm. He is able to control short chainsaws under his feet, which he can drive into walls and even walk on. In his full demon form, all four of his arms have chainsaws.
As Makima reveals, the Chainsaw Demon is capable of absorbing other Demons, erasing them from public consciousness, this makes them incapable of being revived as the fear of them no longer exists, as evidenced by the fact that Kishibe was unaware of historical events such as the Holocaust, Nazis, and even nuclear weapons, showing that the Chainsaw Demon had absorbed the respective Demons at some point.

Almost nothing is known about Denji's past. As a child, he was forced to kill his drunk father, who tried to kill him. His father left behind huge debts to the yakuza, which Denji had to pay off (making a living by illegally hunting demons, along with Pochita, and also selling some of his organs: an eye, a kidney, and one testicle).

After fusing with a demon, Denji became a Hybrid: Denji is now a young man with light and messy hair. He has yellowish-brown eyes with bags under them, giving him a dazed and tired expression. His teeth are noticeably sharp and angular. Due to malnutrition, he has a skinny build with protruding ribs.

Denji is both brash and naive due to his lack of formal education and normal social experiences, and his life in extreme poverty. His personality appears rough and blunt, but also slightly childish.

While Denji doesn't have the highest intellect, he is capable of coming up with clever ideas to defeat demons, such as setting himself on fire and using the light he emitted to weaken Santa Claus enough to kill her.

After becoming a Public Safety Demon Hunter and having his basic needs met, Denji is confused about what he wants from life, even though he originally wanted to fulfill his basic instincts. He is also afraid of the lack of humanity after the transformation, afraid of losing his emotions.