Former human name: Michikatsu Tsugikuni Role: Upper Rank One; highest-ranking Kizuki. Kokushibo is tall and imposing, with long black hair, a muscular build, and six eyes arranged across his face. His body bears distinctive flame-like markings, and his appearance becomes increasingly monstrous as he transforms. He is quiet, formal, disciplined, and extremely serious. Unlike many demons, he retains a strong sense of warrior etiquette and is obsessed with perfecting his abilities. His fighting style is based on Moon Breathing, which he developed from his experience as a former Demon Slayer. His Blood Demon Art allows him to manipulate his demonic flesh and produce enormous numbers of unpredictable crescent-shaped attacks alongside his swordsmanship. He also possesses the Transparent World and extraordinary sensory abilities.

Role: Upper Rank Two. Doma has an exceptionally beautiful, almost doll-like appearance: pale skin, long platinum-blond hair, and rainbow-colored irises containing multiple rings. He usually wears elaborate religious-looking clothing and maintains a permanently pleasant smile. His personality is one of the most disturbing contrasts in the series. He is cheerful, polite, charismatic, and seemingly affectionate, yet he has essentially no genuine emotional attachment to other people.

Role: Upper Rank Three. Akaza is a muscular, athletic demon with pale blue skin covered in dark blue stripe-like markings. His short pink hair and vivid yellow eyes make him immediately recognizable. Unlike Doma, Akaza genuinely values certain human qualities. He is intensely obsessed with strength, martial discipline, and becoming stronger. He respects powerful opponents and despises what he considers weakness. He is aggressive and competitive but follows his own personal principles.

Role: Original Upper Rank Four. Hantengu appears as a tiny, elderly, frightened-looking demon. His seemingly pathetic appearance hides an extremely complicated ability.Hantengu is cowardly, paranoid, dishonest, and constantly portrays himself as the victim. His greatest survival ability is concealing his true body while his emotional manifestations fight for him.

Role: Replacement Upper Rank Four. Nakime is a pale woman with long black hair who normally sits silently while playing a biwa. She has an extremely reserved, expressionless personality and rarely speaks unnecessarily. She controls the Infinity Castle, an enormous supernatural dimension. By manipulating the castle's structure.Her ability made her extraordinarily valuable to Muzan because she could control the battlefield on a massive scale.

Role: Upper Rank Five. Gyokko has one of the strangest appearances among the Upper Moons. His body emerges from decorative pots, his facial features are arranged unnaturally, and his appearance becomes even more bizarre when he enters his transformed state. He considers himself a great artist and views disturbing creations involving humans as masterpieces. He is vain, arrogant, easily offended, and obsessed with having his "art" recognized.

Role: Shared Upper Rank Six. These siblings function as a single Upper Moon position. Daki appears as a beautiful courtesan with extremely long black hair, that turns white with bright green tips elaborate clothing, and a glamorous appearance. Gyutaro, her older brother, has a much more gaunt and intimidating appearance, with greenish skin, messy hair, and prominent markings. Daki is vain, temperamental, possessive, and obsessed with beauty and status. Gyutaro is bitter, jealous, suspicious, and fiercely protective of his sister. Despite their cruelty, their bond is extraordinarily strong. Their survival is directly connected: both siblings must be defeated for the pair to truly be eliminated.

Role: Replacement Upper Rank Six. Kaigaku was formerly a Demon Slayer and Zenitsu Agatsuma's senior under their shared teacher. As a demon, he retains his arrogant, resentful person. He is proud, competitive, selfish, and deeply concerned with proving that he deserves recognition.

Rank: Demon progenitor; leader of the Twelve Kizuki. Muzan has multiple appearances throughout the story, but his most recognizable human disguise is that of a pale, elegant man with black hair and red eyes. He can completely alter his appearance and biological structure. He is calculating, secretive, controlling, and intensely concerned with achieving perfect immortality and conquering his weakness to sunlight. He views other demons primarily according to their usefulness to him and maintains absolute authority over the Twelve Kizuki. He is the source of the demons created through his blood and commands the Twelve Kizuki.