Within the demon hierarchy created by Muzan Kibutsuji in Demon Slayer: Kimetsu no Yaiba, the Lower Moons represent the lowest level within the Twelve Kizuki.
These 6 Lower Moons can, in turn, be divided into two groups: the three most powerful, from 1 to 3, and the weakest, from 4 to 6. These latter three Moons show a common pattern: forced obedience, constant fear of Muzan, and clear fragility against demon slayers, which explains their short tenure within the organization, despite possessing superior strength to ordinary demons.
If you wish to learn more about them, you may continue reading, but at the risk of encountering significant spoilers about these characters.
Kamanue: Lower Moon Six
Kamanue is the first demon shown during the Lower Moons' meeting after the group's reorganization. His appearance is brief but significant for understanding the dynamic of terror imposed by Muzan.
Furthermore, he conveys fragility and insecurity: he has a pale and nervous appearance, with dark marks on his face, slit eyes, and a constantly altered expression that reflects the permanent fear under which the Lower Moons live.
During the meeting, Kamanue initially doesn't recognize Muzan due to his change in appearance. This mistake reflects the distance and true unfamiliarity many demons have with their creator.
Later, Kamanue mentally expresses his annoyance when Muzan calls the Lower Moons weak, unaware that Muzan has the ability to read minds. This act of implicit disobedience is enough for Muzan to eliminate him immediately.
His death demonstrates that within the organization, there is no room for doubt or questioning, not even internally.
In the manga and anime, no exclusive techniques or a unique Blood Demon Art of his own are ever shown. The work only confirms his rank as Lower Moon Six within the Twelve Kizuki, which indicates he possessed physical and regenerative abilities far superior to those of a common demon.
Rui: Lower Moon Five
Rui is one of the most developed cases among the Lower Moons.
Before becoming a demon, he suffered from an illness that severely limited his mobility and quality of life. He was transformed by Muzan with the intention of granting him strength, but this change completely altered his psychology.
After his transformation, Rui developed a distorted view of family. After a conflict with his human parents, he ended up killing them, although he initially believed they weren't his real parents. However, his mother's dying words revealed that they did love him, causing a deep emotional crisis within him.
From that moment, Rui attempted to reconstruct a "perfect family" among demons, imposing strict roles of obedience and hierarchy. This structure was not based on love, but on fear and submission, reflecting his inability to understand real human bonds.
He has the appearance of a child with extremely pale skin and black hair with reddish tips. His face and part of his body are covered in red marks similar to threads or spiderwebs, visually reinforcing the spider theme that dominates the entire Mount Natagumo arc, where he confronts the demon slayers in combat.
His eyes show the kanji corresponding to his rank as Lower Moon Five within the Twelve Kizuki.
His childlike appearance contrasts with a cold, manipulative, and extremely violent personality, especially when he feels his "family" is not fulfilling the role he deems correct.
In combat, Rui uses a Blood Demon Art based on almost invisible and extremely sharp threads. These threads can cut flesh, bones, and even nichirin blades, as well as serve to control other demons like puppets.
Rui can also create threads reinforced with his own blood, greatly increasing their toughness and destructive capability.
Thanks to this ability, he transforms Mount Natagumo into a massive network of spiderwebs used both for attacking and for controlling the combat terrain.
Furthermore, he possesses advanced regeneration, great speed, and superior reflexes, characteristics that make him one of the most dangerous Lower Moons shown in the series.
Rui is defeated in the Mount Natagumo arc by the Demon Slayer Corps, specifically by Giyu Tomioka, after previously confronting Tanjiro and Nezuko.
Mukago: Lower Moon Four
Mukago appears during the same Lower Moons' meeting, displaying an extremely fearful and submissive demeanor from the start.
She has the appearance of a young demon girl with pale skin, dark hair partially tied back, and pink eyes where her rank as Lower Moon Four is engraved.
Her expression is usually nervous and frightened, reinforcing the image of constant insecurity she conveys throughout the meeting with Muzan.
Unlike other more aggressive or confident demons, Mukago stands out for an attitude clearly dominated by fear and anxiety.
She doesn't recognize Muzan until he demands direct obedience.
When Muzan eliminates Kamanue and announces the weakness of the Lower Moons, Mukago tries to justify her position, but her fear is evident. Muzan detects this fear towards demon slayers, making her an immediate target.
Despite her attempts to deny it, Mukago is unable to hide her insecurity. Muzan interprets her as a useless Moon and executes her without discussion, crushing her with his power.
Her case clearly represents the psychological fragility within the group: not only are they physically weak, but they also lack emotional stability in the face of the human threat.
Due to her swift execution, no exclusive techniques or individual powers developed for the character are ever revealed. The work only confirms her position as Lower Moon Four within the Twelve Kizuki before she is killed by Muzan.
