Denji is a fair-skinned teenage boy with scruffy blond hair that has strands sticking up and falling messily around his head. He has yellow-brown eyes and bags underneath, resulting in a dazed and tired expression. His teeth are noticeably sharp and angular. Due to malnutrition in his childhood, he has a scrawny and undernourished build with protruding ribs, relatively long-looking, almost lanky legs, and slim wrists, and due to the stress of what he did for a living, he’s often mistaken for being older than he actually is. He spent much of his time wearing the standard Public Safety Devil Hunter uniform, consisting of a white shirt, tie, and slacks. He wore the uniform carelessly, his shirt wrinkled and sleeves rolled up. If his chainsaw cord is pulled while he has enough blood for the transformation, then his head will morph into a demonic, mechanical shape with long, jagged fangs and a chainsaw handle on the back. Large chainsaws will emerge from his forehead, arms and legs, he is able to retract and extend any of them at will.[8] If Denji's chainsaw cord is pulled while he does not have enough blood, then a chainsaw blade will partially emerge from his face. Denji also harbors a fear that his seeming lack of empathy and attachment after his transformation is a sign that he is losing his sense of humanity. While transformed into his Hybrid form, Denji becomes extremely ruthless, aggressive, bloodthirsty and sadistic, releasing his most deranged side while facing other Devils, to the point of enjoying killing them. He also displays a twisted and sarcastic sense of humor.