Douma

Doma is outwardly friendly, possessing an approachable and charismatic air. Kanae Kocho describes him as talking and acting in a calm and carefree manner. However, it is soon revealed that Doma has psychopathic tendencies. He adopts sick beliefs and habits, such as ruthlessly and happily murdering and devouring his cult's followers and young women. He believes he is saving them from their suffering by letting them live inside his body.

Under his carefree and unassuming demeanor, Doma is a cold and calculating individual with an extremely keen intellect. His high intelligence may be the reason why he looks down on humans, genuinely believing that they are pathetic and stupid. He even cried out of pity for them. His condescending attitude towards humans was also showcased when he was decapitated by the combined efforts of Shinobu Kocho, Inosuke Hashibira, and Kanao Tsuyuri. He felt insulted to be killed by individuals whom he thought lowly of.

It is later revealed that Doma is clinically apathetic, completely emotionless, and unable to experience proper emotions. Doma himself admitted that the concept of emotion was completely foreign to him, even as a human. Aware that this is abnormal, Doma compensated for his empty heart with his own charisma. He learned to express his carefree demeanor enough to deceive all but the most keen observers.

Despite his innate apathy, he appeared angry when Kanao insulted his inability to feel real emotions, dropping his kindly façade and outright trying to kill her. His apathy could be tied to his psychopathy, or even be the source of it. This is shown when his mother murdered his father and then proceeded to kill herself all while being observed by Doma when he was a child; Doma didn't show any sign of grief or shock, but instead complained that their blood made the room stuffy.

In spite of his apathy, Doma has a disturbing habit of primarily eating young women, as evident by most of his cult followers being women. One exception to this was Inosuke's mother, Kotoha Hashibira, who Doma didn't want to kill and instead wanted to keep by his side until she died of natural causes, though he eventually killed her when she tried to escape. The reason for this unique behavioural trait is still currently unclear, though it is implied that the reason is because women provide more nutritional value for demons as they can nurture babies.

During his interactions with fellow Upper Rank Akaza, he showed no negative reactions to him delivering two fatal blows to his head in annoyance, one with Akaza swiftly punching the upper part of Doma's head off, then punching his jaw off. In fact, he considered this to be their form of personal "greeting" between two "best friends." Doma has even implied that he actually enjoys these physical abuses as seen when he morbidly asked Muzan with excitement on what type of extreme self harm he should inflict on himself as punishment for his failure, and again expressed delight upon the severe pain he felt at Shinobu Kocho's numerous attempts to poison him to death and even cheerfully expresses his delight on the feelings and sensations of the poison destroying his body and how he might actually grow to "like" it.

Doma is a very tall young man with a lean but toned and muscular body, who is of a notably pale complexion and possessed unusually long, pointed nails that appeared to be stained with a pale blue color. He possesses long platinum blond hair that he wore parted to his right, the shorter parts around his face seeming to flare out to either side around his head, curving backwards with one lock slanting down to the right of his face to fall between his eyes, while the longer parts were left to drape centrally down his back in a thinning spiral.

His eyes have been described to be incredibly rare and beautiful, as, in color, they appeared to be made up of an array of rainbow pastel tones that fade into one another as they circle his irises, this unusual appearance even causing people to believe Doma is a blessed being who could communicate with the gods.

Doma wore a blood-red turtleneck of a design that made it appear that the section between his neck and upper chest is covered by a black substance that looks like it's dripping slightly down his body, this same design repeated at his wrists and down his hands, as well as on the small, circular "blood stain"[14] he adorned on his head. Below this, he wore a pair of straight, tan-colored hakama pants of a pinstriped design, their cuffs visibly loose, which he secured with a pale green-tinged golden belt, its buckle a bright silver. He also only wears plain black tabi socks on his feet.