The Gravediggers: The branch that digs up the graves of the recently deceased leaving no visible signs of disturbance and devours the bodies; they're actually officially employed as the groundskeepers of the cemetery, but no one knows that they're demons. As part of their secondary duties, they sell imported drugs in the streets of wherever they're currently based to increase the mortality rate and keep up the steady supply of food. The money from their sales and grounds-keeping jobs gets sent to the Mystery Eater so he can keep running his organization and bribe human politicians, if needed.
The Suicide Squad: Up in the forests and mountains of towns across Japan, there are distinctive stone idols where suicidal people leave an offering, which the demons use to track them down and discreetly kill them in their sleep. The people who come here cannot bring themselves to do it and wish to go quietly, so the Squad is a specialized force of demons that has honed the art of killing while making it look like a suicide. The people usually leave behind suicide notes in their bedrooms, but the demons will forge one in case they didn't. So despite the fact that the body disappears and is devoured, nobody suspects a thing. The stone idols are more of an urban legend; the deaths are believed to have been carried out by the victims rather than a third party. They likely wrote down their last words and drowned themselves somewhere. The bodies just haven't been found, or so the story goes. As part of their secondary duties, members of the Suicide Squad are master sculptors, who secretly made the stone idols in the mountains and sell their other figures as souvenirs in shops. The Mystery Eater has provided them a scheme that secures them a steady supply of food, so in exchange, they send him the earnings they get from their day jobs.
The Lab Rats: They run covert clinics that raise humans in captivity and artificially inseminate them with donated sperm. This branch is also researching ways to enhance demons' strength, speed, and regeneration, so they can regrow their entire bodies even if all that's left is a finger.
The Party Animals: They throw themed parties that draw large crowds, where attendees are marked, killed in their sleep, and picked up at night. The target-shaped rashes are dismissed as sexually transmitted diseases from these drunken orgies. Everyone dresses as a demon, so it's hard to tell who actually is one.
The Dungeon Masters: The darkest branch of them all, they operate a string of brothels that draw in men and women looking to sell their bodies. Business hours run from morning to late in the night, and any revenues not used to cover building expenses are contributed to the workers' well-being. What they want is not money but a steady supply of food. The female employees run a high risk of getting pregnant, and if they do, they're pulled off the shelves and carted away somewhere as merchandise, perhaps to a dark dungeon, or to an abandoned factory, or to some other temporary base. They're cared for throughout gestation, and the Mystery Eater himself pays them a visit when they've all born children. The little ones are promptly separated and devoured, while their mothers return to work. Keeping them silent involves a tremendous amount of physical and psychological abuse. They're told they're poor, useless, and cast aside by humanity, that they're property and have no rights in a court of law. Those who won't be broken are instantly torn to pieces. Eventually, the women begin to believe that this life is what's best for them, and when the day comes that they grow shriveled and unmarketable, they're consumed too. The worst part is that few will miss them, not the civilians who appreciate the cleaner streets, not the abusive husbands who drove them from their homes, not their one male coworker who was eaten long before, and certainly not the clients, who'd moved onto the next piece of meat. The Dungeon Masters have a sick practice of boiling the victims alive in a drum of hot water before tearing into them.
The Warmongers: The branch with the most ambitious yet rewarding operation, they instigate tensions with overseas powers in the hopes of starting wars and leaving bodies for the demons to eat, or mysteriously sink ships and consume crews. Also if a ground war throws Japan into chaos, it won’t be able to focus on the demons as much, and they’ll run wild and devour humans virtually unchecked. Some of their demons fight enemy forces on the front lines; this allows the Warmongers to promote coexistence with humans, by pushing the narrative that they died for them. They recovered a lot of missing bodies from the Russo-Japanese War and froze some as emergency rations to feed the Mystery Eater’s organization if needed. This branch also negotiates with foreign demons to obtain their country’s dead humans, in exchange for something of equal value, of course.
The Farmers: Different from the Lab Rats, their plan is to raid towns, erect walls, and turn them into breeding grounds where they’ll raise humans like livestock. Probably the most mysterious and least active of the branches at this point in the story.
The Gladiators: Run underground fighting rings that draw in humans seeking to take revenge on demons and pit them against actual demons in bloody battles. The humans are naïve, thinking they can kill demons with just swords and driven solely by blind hatred, or they’re adrenaline junkies, or poor men looking to win prize money. Either way, they’re killed in front a crowd and devoured backstage. This hypothetical branch is the biggest threat to the Demon Slayer Corps’ membership, since instead of going through grueling years of training and becoming actual demon slayers, young people are caught up in this fantasy and think they can take shortcuts, start killing demons right away. That’s how they’re lured to their deaths.
The Servers: They own restaurants popular with humans and serve ordinary food, but they have a secret demon menu after dark where they serve cooked humans as gourmet dishes. Flesh is obtained from large open fields designated as private property across the country. Anyone who tries to build, picnic, or trespass there is hunted down and killed in perfectly legal fashion.