𝒂𝒌𝒂𝒛𝒂, 𝒅𝒐𝒖𝒎𝒂 𝒚 𝒌𝒐𝒌𝒖𝒔𝒉𝒊𝒃𝒐★

Kokushibo was a reserved being shrouded in utter mystery. At the Upper Moons' Gathering, he proved to be punctual, rule-abiding, and placed a high value on the hierarchy of the Twelve Demon Moons. He was also humble, as he did not hesitate to admit failure or complain about any difficulties, rather than acknowledging the strength of his opponent. He displayed a strong sense of loyalty toward Muzan Kibutsuji, and most of his actions were done with the sole purpose of fulfilling Muzan's goals. Despite displaying a reserved outward character and humility, he was also quite cold: his words could be harsh, especially when reprimanding people. His threats were nothing short of cruel and overwhelmingly serious, and he demanded absolute obedience. He had a complex relationship with his human past. He showed some warmth toward his descendant, Muichiro Tokito, praising his skills and resolve, and was determined to turn Muichiro into a Demon to save his life. At the same time, he refers to Muichiro and his abilities as the natural result of his "cells" being passed on. As a result, it is unclear whether he holds any true attachment to him or if it is the result of an overblown narcissistic pride. Watching the two demon-slaying brothers, Sanemi Shinazugawa and Genya Shinazugawa, makes him nostalgic. Fighting Sanemi caused him to recall dueling an ancient Wind Pillar to improve his skills. It is revealed that during his past as a human, he harbored a huge resentment of spite and envy towards his younger twin brother, Yoriichi Tsukiguni, due to his natural talent and abilities since birth. These feelings of jealousy and contempt eventually intensified further upon seeing his brother age and having survived to said age despite awakening his Demon Slayer Mark, which was supposedly supposed to doom him to death at the age of 25.

Kokushibo was a Demon who retained his human features despite having devoured countless people for 400 years. He maintained several rather unusual characteristics: he was a tall man, with a pale skin tone and an athletic and muscular build; his hair was long and black with burgundy edges, held back in a long ponytail that reached almost to the height of his lower back. On his face, he possessed a series of flame-like markings covering the left side of his head and the right side of his neck; these markings were, in his human stage, his Hunter's Mark. Kokushibo's most emblematic feature, and at the same time, one of his most sinister identifying marks, were his three pairs of eyebrow-less eyes, which had a yellowish iris and red sclera divided into segments. In the center of his eyes, his numbering as the Upper Moon One is located, identified with the kanji for First Crescent (壱 上弦, Ichi Jōgen?), indicating his dominant position within the Upper Moons. As for his clothing, he wore a kimono with patterns in violet and black tones with a white haneri (undergarment in a kimono), a black hakama and a white obi belt. He owned a katana made from his own flesh and bones, which was completely decorated with eyes on the cutting blade, the tsuba and the tsuka. The guard was also covered in flesh and eyes to completely increase his degree of peripheral vision. After Sanemi and Himejima were able to decapitate him, Kokushibo managed to regenerate his head, transforming his body into a completely grotesque version of himself, with several fangs emerging from his mouth, a pair of horns coming out of his head and several sharp appendages.

Doma may have appeared to be a friendly and charismatic individual, but far from reality, he was a deadly and calculating being. Believing that he was saving them from their suffering, he happily devoured his followers and other young women. While he may have seemed concerned for his comrades, he felt no genuine sorrow for their deaths. His predisposition to devour women is justified in a rather twisted way since, according to his criteria, women possess more nutrients than men, which allows him to further increase his power. In the end, these preferences proved to be part of his own downfall since a woman of all people, Shinobu Kochō, the Insect Pillar, devised an entire strategy that involved sacrificing her own life in order to defeat him. He was quite nihilistic and lacked human emotion, admitting that even during his human days, the entire concept of emotion was completely foreign to him. Aware that this was abnormal, he compensated for his empty "heart" with lies, learning to fake his emotions enough to fool all but the most keen observers. He is shown to have been a psychopath, lacking empathy even towards his dying parents, complaining of the smell of blood they gave off. In addition to his inability to feel emotions, he has also displayed inhuman amounts of pain tolerance, suffering from Congenital Insensitivity. He has been shown to have several disturbing and unsettling habits, such as sticking his finger into his skull, drilling a hole directly through his temples, and then stroking and manipulating his brain to stimulate his memories of his long life with a completely serene expression on his face. During his interactions with his fellow Upper Moon member, Akaza, he showed no negative reactions to his constant fatal physical attacks and head-exploding. In fact, he considered this to be his personal form of "greeting" between two "best friends."

Douma was a Demon who retained some of his human features with slight subtle differences; notable for his moderate musculature, long, pointed pale blue nails, pale skin, and thick black eyebrows. His hair could appear silver or pale golden blonde. It was shorter on the left side and the rest extended to the right, with several uneven strands extending in both directions. Some of his hair fell forward, covering part of his forehead and leaving both his eyes and eyebrows visible. He often wore his hair loose, with the ends trailing down his back in a spiral-like shape. Many have described his eyes as incredibly rare and beautiful, as their color appears to be a variety of rainbow pastel hues that fade into each other as they surround his irises; this unusual appearance even makes people believe in Douma. He is, according to his followers, a blessed being who can communicate with the gods. Like all the superior moons, they have the kanji in both eyes, in his case that of Second Crescent (弐 上弦,, Ni jōgen?) and previously that of Sixth Crescent (陸 上弦,, Roku jōgen?) which accredits it as one of the twelve demonic moons. As for his clothing, he wore a long-sleeved red shirt tight to the body allowing his muscles to be noticeable while the collar of the shirt was surrounded by a black pattern giving the impression of a dripping stain. He wore beige pants with black lines held with a gold belt with a silver buckle. On other occasions he was seen wearing a type of jacket similar to a black short-sleeved haori with wide pink edges and patterns in black rectangles and squares. Accompanied by a large black crown with gold designs and black ribbons extended at the ends. He usually carried a fan.

Akaza was a stubborn, headstrong, and battle-mad Social Darwinist who enjoyed fighting, especially against powerful Demon Slayers. He would purposefully drag out fights to savor every moment, always praising his opponents when they displayed powerful techniques or landed blows against him, often commenting that their techniques and swordsmanship were magnificent and intriguing. Akaza looked down on anyone he deemed weak, so much so that his skin crawled at the sight. He genuinely respected those who were strong in his eyes, demanding to know their names and not stopping until he discovered them; he would recall all the names of past strong opponents and memorize them as a tribute to their strength. Akaza also presented an opportunity for those he acknowledged strength in to become Demons, believing that preserving their refined techniques and skills was the right thing to do and feeling pain at seeing the deterioration of those blessed with extraordinary gifts as they age, going so far as to kill them to preserve their magnificent skill himself if they refused his offer to become a Demon. He also did not discriminate against strong warriors who were previously weak, as shown when he praised and complimented Tanjiro Kamado despite initially attempting to kill him for how weak he was during their first encounter, even going so far as to thank Kyojuro for Tanjiro's growth. Akaza was a firm believer in Social Darwinism, believing that the law of nature dictates that all weaklings must be eliminated. Akaza had a deep-rooted psychological need to become stronger, and while he usually respected the strong, he did not get along with his fellow Upper Rankers, seeing them as his rivals. He was especially antagonistic and somewhat jealous of the two Higher Ranks above him.

Akaza was a very muscular young man of average height, with skin so fair it looked white with a bright green tinge, decorated with a pattern of thick blue lines reminiscent of the criminal tattoos he had as a human. Akaza had short, bright pink hair that fell fluffy around his head, and yellow, inward-slanting eyes with pink eyelashes and blue sclera that resembled broken glass. The kanji for High Rank (Jōgen?) was etched into his right iris, and the daiji for Three (San?) was etched into his left. Lines on his face curved through each of his eyes from below his ears to above his temples, another blue line ran from the center of his hairline to the bridge of his nose, with two more lines running around his neck, and three more branching off the bottom one towards his torso. The middle line ran straight down his chest to the middle of his stomach, and the other two branched out at the sides over each side of his chest to join the other two lines. This same three-line pattern was also repeated around his waist. On his arms, lines ran down the front of his shoulders that joined with two more, which circled his biceps before continuing down to his wrists, below which each of his fingers was also dark blue with an orange nail, his toes also shared this unusual appearance. Akaza was scantily clad, sporting only a short, sleeveless, dark purplish-pink haori, slashed at the waist, open to reveal his chest, and decorated with a square pattern on the back. Beneath it, he sported loose-fitting white pants, rolled up to just below his knee with a blue rope belt to secure them at his waist. Akaza preferred to go barefoot, but wore a pair of strings of large, round, pink pearls around his ankles.