In a world where katanas are the most reliable self-defence weapon, encountering a demon, especially one of the 12 Kizuki, is undoubtedly horrifying. It is the organisation of the 12 most powerful demons, who report directly to the demon kingpin, Muzan Kibutsuji. Even such a powerful organisation was divided into the upper and lower six moons. We aren’t concerned about the Lower Moons because Muzan swallowed most of them before they could shine. Instead, we have ranked the Six Upper Moon Demons, who have long been a source of consternation for the Hashers.
Daki, although being an Upper Moon 6, posed little threat to Sound Hashira Tengen Uzui. He slashed off her head as though it were nothing; even Inosuke’s damaged sword could behead her. I doubt she would have become an Upper Moon without Ryutaro’s help. Muzan remarked that Daki was the obstacle that caused the death of the first Upper Moon 113 years after Daki and Gyutaro were killed. However, killing seven Hashiras in her life is more than enough accomplishment for her to consider herself valuable. She could transform her body into an invincible Obi that could withstand even the most potent Nichiren blades.
Kaigaiku is an Upper Moon 6 who took over for Gyutaro and Daki during the Hashira training arc. He was Zenitsu’s senior under Jigoro Kuwajima, the former Thunder Hashira. Despite being superior to Zenitsu, he detested Zenitsu for being their teacher’s favorite. He became enraged when he learned that Grandpa Jigoro intended to make both of them his heirs. This deep hatred increased over time until he met Upper Moon 1, Kokushibo, who offered him the chance to become a monster. He never regretted becoming a demon because he craved the attention he felt he lacked. Worse, his desire for power morphed into a need for human blood.
Gyutaro is the vicious demon who dwelled in the shadows of the Entertainment District and stood firm in his protection of Daki. In his demonic lifetime, he killed nearly 15 Hashiras and was the primary reason for Tengen Uzui’s early retirement. He was always looked down on and despised simply for being human. However, his endurance limit was shattered when the harsh world took away his precious sister. Daki was burned alive by a samurai for slashing his eye with a comb. Doma discovered helpless Gyutaro with her half-dead sister when he converted them into demons. Gyutaro had a lethal pair of sickles that he could boomerang in every direction with his Blood Demon Art of Flying Blood Sickles.
Gyokko and Nakime:
Gyokko is the demon with the most unusual look and the demon about whom we know the least. He raided the Swordsmith town and came close to eradicating it. He was tough to capture due to his ability to teleport from one vessel to another. He could call fish-like demons and unavoidable spine-throwing fishes due to his passion for fish. He even imprisoned Mist Hashira, Muichiro Tokito, in a water jail and nearly killed him. Nakime is the demon responsible for erecting the Infinity Castle, which gave the ghouls the upper hand in the final battle. She has known Muzan for a long time and took over as Upper Moon 4 after Hantengu died. She is arguably the most annoying demon due to her unique ability to radically transform the environment around her. She stymied two of the strongest Hashiras like it was nothing. She is, however, frail in terms of sheer strength and endurance.
Hantengu, the original Upper Moon 4, raided the Swordsmith village with Gyokko. He initially seemed weak but turned out to be the more problematic one. His specialty is to split into different demons after getting cut. The demon slayers were late at recognizing his powers and went on slicing them, only to find themselves surrounded by four more demons. The worst part is that not even chopping their head off would kill them since the actual body was somewhere else. Thanks to Tanjiro’s enhanced sense of smell, he successfully detected his sixth body, where his life force resided.
Akaza was the overpowered demon who horrifically killed Flame Hashira Kyojirou Rengoku. We didn’t know we would mourn the same devil later in the series. He used to steal money for his father’s treatment when he was a teenager. His father eventually committed suicide because he couldn’t stand the guilt of living off stolen money. He attempted to build a new life with his master and her daughter, Koyuki, but that was also taken from him. Doma is the demon for whom none of us feels any remorse. He was the insane lunatic who reveled in consuming his prey, especially young females.