Nakime

Nakime shares many similarities with the former Lower Moon Six, Kyogai, both use a demon blood art that allows them to freely manipulate a certain structure at will, both use a musical instrument to utilize their individual techniques, and both received their epithets based on these instruments.
Nakime also had a husband but no children. After several years of relationship, she killed her husband with a hammer.

Demon Blood Techniques
Although Nakime's Blood Demon Art was not as combat-ready as the rest of the Upper Moons, her ability was just as strong, if not stronger, than her comrades in terms of utility and power, as she alone could control and manipulate an entire fortress at will.

Fortress Manipulation - Nakime has the ability to manipulate and control the Infinite Fortress by playing Biwa, able to bring anyone into the fortress and able to create entrances and exits wherever she wants and attach and root her hair to the wall nearby inside the fortress, she can control the position of the fortress as she likes, moving and changing the position of various walls as she wishes.
Eye Severing - Later, after attaining the rank of Upper Moon Four and presumably receiving more blood from Muzan, she demonstrated a new ability to create and separate multiple eyeballs from her body, allowing her to spy on others from a great distance. With this new ability, she managed to locate the locations of almost all the Demon Slayer Corps members throughout Japan, as well as the hidden mansion of Kagaya Ubuyashiki, who had gone to great lengths to hide its location even from high-ranking members of the Demon Slayer Corps.

Nakime made some money playing the biwa, but she was a completely unknown performer and her husband was always gambling, so she lived in poverty. One day, when her husband sold her only biwa kimono and spent the money on gambling, Nakime became so angry that she beat him to death with a hammer. After that, she still had to work, so she performed in her torn kimono, earning disapproving looks from the audience, but when she played the biwa with strong and trembling hands, she was praised. From then on, she began playing the biwa after killing people, and every time she did so, the sound of her biwa was praised. She randomly targeted Muzan and tried to kill him, but failed. However, he was so pleased with what she did that he turned her into a Demon.

Nakime is emotionless and very taciturn. She usually gives straightforward answers and can sometimes come across as rude. Nothing is known about her early personality.

During her anime debut, Nakime took the form of a pale woman with a grayish skin tone, sharp, blue-painted nails, and especially red lips that contrast sharply with her skin tone. She had glossy, waist-length dark brown hair with two chin-length strands left to frame her face and long bangs that covered her eyes.
Nakime wore a simple black kimono with a striped pale brown obi. She always appeared with a wooden biwa.
Since becoming an Upper Moon, Nakime had removed her bangs to avoid obscuring her face, revealing only one large pink eye with the number "four" written on it. The upper portion of her face was also exposed and a darker gray than the rest of her skin, with prominent veins surrounding one eye.