Mukago appeared to have sickly, yellowish skin, two dark red stripes across her cheeks, and a pair of white horns protruding from either side of her forehead. Her eyes were gray with white rings around the sides and dark red sclera with the kanji for "Four" carved over her left iris, framed by a set of notably long eyelashes. She also possessed chin-length white hair with shorter bangs between her horns.
Mukago wore a plain red kimono with a black-and-white fur-lined collar tied up at the back with a large, dark purple bow.
Out of all the Lower Ranks, Mukago was shown to be the most cowardly. As stated by Muzan Kibutsuji through reading her thoughts, Mukago had no intention of battling the Demon Slayer Corps' Hashira and planned to flee at the mere mention of one, noted to have done so numerous times. When Muzan learned of this, Mukago attempted to appease him and beg for mercy.
After all of the remaining Lower Ranks gather together at the Infinity Castle, Muzan appears before them in his female form. He regards them with annoyance and tells them to lower their heads and kneel in front of him. After they all do so, Mukago utters that she's sorry to have been ordered to bow, as she didn’t recognise Muzan in his current form. Muzan angrily asks why she's speaking without permission, telling her to silence herself and not to talk unless directly asked a question. As she cowers in fear at her feet, Muzan goes on to explain the death of Rui, the only Lower Rank who wasn't among the ones gathered before him, and asks the remaining Demons why they're so weak.
Muzan lectures them about how being in the ranks of the Twelve Kizuki isn’t the end; it is only the beginning of what is to come. He states their sole purpose is to consume blood so they can be of use to him. Muzan angrily retorts that it has been over a century since the Upper Ranks were last replaced, yet the Lower Ranks are replaced all the time, to which Kamanue thinks to himself that he can’t just tell them that.
Capable of reading the minds of those he has shared blood with, Muzan angrily asks Kamanue why they couldn’t be told that, expanding and extending his arm into a tentacle to grab the Lower Rank by his neck and lift him into the air. Kamanue attempts to apologize, but is promptly eaten by Muzan as Mukago and the rest of the Lower Ranks keep their heads lowered in a shocked silence.
Next, Wakuraba thinks to himself that he's also going to be killed, so he needs to do more in order to keep his position as a Lower Rank, and, simultaneously, Mukago thinks about how she runs every time from the very mention of a Hashira. Muzan asks if they fear the Demon Slayers more than they fear him, to which a terrified Mukago exclaims that she does not but Muzan challlenges that and states that he is sure that every time she encounter a Hashirai level Demon SLayer, her only thoughts are of escaping; she denies this as well and says she would fight with her life on the line for him. Muzan asks her if she is denying what he, the Demon lord, was saying, and, as Mukago begins to apologize and cry, another bout of Muzan's tentacles crushes her into the ground, killing her.
Abilities and Powers
Little is known about Mukago's strength and abilities as a Demon, but it is assumed that she must have been much stronger than an average Demon and superior in power to Rui and Kamanue, as she was given a higher Lower Rank position than them.
- Mukago's name was revealed in the first fanbook.