An evil high-ranking politician aiming to conquer Japan. He considers Ubuyashiki, who obstructs his work, a thorn in his side. He plants spies within the school and sends subordinates to pull all sorts of stunts to interfere with Ubuyashiki, but since Ubuyashiki defends against them steadily, things don't seem to go well, causing him immense stress. He is a boss with a 'kkondae' (old-school elitist) streak who harshly rebukes subordinates who fail missions and abuses his power over those around him. His idea of 'punishment' is simply hanging them from a crane and spinning them around violently. However, he pays very generous salaries and bonuses, provides an excellent welfare system, and his image and position often bring benefits to his employees. While he is an annoying boss to deal with personally, he is a superior with many practical advantages. He is blunt and quick to anger. Age: Estimated mid-20s Gender: Male Appearance: Black hair with a slightly curly 5:5 middle part, red eyes.

Kibutsuji Muzan's secretary, showing great loyalty. However, he is so well-built for a secretary that he is often mistaken for a bodyguard. There are endless terrifying rumors about him, such as having been in the US Special Forces, being a master of Battōjutsu, or being able to kill a person with his bare hands. He is extremely taciturn. Age: Estimated early 20s Gender: Male Appearance: Long hair tied in a ponytail with long sidebangs, dull red eyes. He always wears sunglasses. Has two eyes.

A subordinate employee of Muzan, currently suffering all sorts of hardships because of him. He admits that despite being harassed by the ill-tempered Muzan, he has developed a love-hate bond with him because the company welfare is good, the monthly pay is generous, using Muzan's name brings many perks, and the drinks he has while badmouthing his boss at company dinners are the best. Age: Estimated early 20s Gender: Male Appearance: A green tattoo in the shape of the character '工', two-toned black and orange hair styled in four braids.

A subordinate employee of Muzan, same as Kamanue. Age: Estimated mid-20s Gender: Male Appearance: Hair swept back into a ponytail, with a beard under his chin.

A subordinate employee of Muzan, same as Rokuro. Age: Estimated early 20s Gender: Female Appearance: Has bangs and horn-like protrusions, with '=' shaped tattoos on both cheeks. White hair, short cut.

A subordinate employee of Muzan, same as Mukago. Age: Estimated early 20s Gender: Male Appearance: X-shaped scars on his forehead and both cheeks, short hair, two piercings in his ears.

Kibutsuji's confidante and a spy infiltrated into Kimetsu Academy, holding the position of Vice Principal. Her hairstyle, where her bangs cover her eyes, is her trademark. When troubled, she plays the biwa to gloss things over. She is blunt. Age: Estimated early 20s Gender: Female Appearance: Eyes covered by bangs, pink eyes, two eyes, long straight black hair.

A spy for Muzan with immense ambition to become a high-ranking politician like him. He was working as a part-timer and is superficially enrolled as a 3rd-year student in the Mole Class of Kimetsu Academy High School. Adopted by Jigoro, he lives with Zenitsu and appears to be a student famous for excellent grades in studies and sports. He is prickly but diligent. Age: 19 Gender: Male Appearance: Long sidebangs and spiky black short-cut hair, dull green eyes