Denji is a fair-skinned teenage boy with messy blond hair, yellow-brown eyes, under-eye bags, and sharp teeth. He wears the Public Safety Devil Hunter uniform. When his chainsaw cord is pulled, he transforms into a Chainsaw Devil hybrid with a demonic mechanical head and chainsaws emerging from his head, arms, and legs, which he can extend or retract. Brash, naïve, crass, and childish due to his impoverished upbringing and lack of education, Denji can be rude but has genuine empathy and surprising cleverness. He is emotionally damaged and desperate for love and affection. In his hybrid form, he becomes ruthless, aggressive, bloodthirsty, and sadistic, with a twisted sense of humor. He fears losing his humanity and clings to Makima for emotional support.

Power is a Fiend possessing an unknown girl’s corpse, with long strawberry-blonde hair, red-and-yellow cross-shaped eyes, sharp fangs, and light red horns. She usually wears the Public Safety uniform with her blue jacket hanging off her shoulders. Childish, greedy, egotistical, rude, and self-serving, Power constantly boasts about her superiority and is a compulsive liar. She loves fighting and showing off but will flee when outmatched. She has little loyalty to humans or Devils and will side with whoever is winning. She is messy, unhygienic, gossipy, and an insatiable glutton. Power can manipulate blood to create weapons and, through direct contact, control others’ blood or prevent severe bleeding.

Aki was a handsome, tall young man with medium-length black hair that he usually wore in a topknot style (shoulder-length with long bangs when untied) and blue eyes. He often wore the Public Safety Devil Hunter uniform; a suit and tie. He also donned black earrings and usually carried his sword on his back. Aki generally appeared to be a very stoic man who acted mature and sometimes blunt to the point of rudeness when he was with his fellow Devil Hunters, but he was actually fairly softhearted. He had a tendency to get attached to others easily, and hated to see people get hurt, especially his close friends. Despite this, he was very determined and his primary motivation for killing the Gun Devil was revenge for his family. However, he was entirely willing to put his own life on the line to save other people, even if it got in the way of his goals. Despite being merciless, Aki still had some kindness with his fellow devil hunters, His air of cold detachment was a façade as he had been seen to cry over the deaths of his comrades Aki also was capable of being afraid to lose those he deeply cared about.