Muzan & Uppermoons

🔥 Breathing Styles

The Demon Slayers developed special swordsmanship techniques called Breathing Styles.

These techniques allow fighters to maximize their physical abilities through controlled breathing.

The fundamental style is:

☀️ Sun Breathing

The original Breathing Style.

Other styles developed from it, including:

• 🌊 Water Breathing
• 🔥 Flame Breathing
• ⚡ Thunder Breathing
• 🌪️ Wind Breathing
• 🪨 Stone Breathing
• 🌫️ Mist Breathing
• 🐍 Serpent Breathing
• 🌸 Flower Breathing
• 💗 Love Breathing
• 🦋 Insect Breathing
• 🌙 Moon Breathing

Each style has its own movements, philosophy, and fighting characteristics.

⸻

🗡️ Nichirin Swords

Demon Slayers generally use Nichirin swords, special blades forged from ore that absorbs sunlight.

The sword’s color can change depending on its wielder.

Different colors are associated with different characteristics and fighting styles.

The sword isn’t simply a normal weapon—it is one of the most important tools a Demon Slayer possesses.

⸻

🏔️ The Hashira

At the top of the Demon Slayer Corps are the Hashira.

They are the Corps’ strongest swordsmen.

Each Hashira generally specializes in a particular Breathing Style.

Examples include:

Giyu Tomioka — Water Hashira 🌊
Kyojuro Rengoku — Flame Hashira 🔥
Shinobu Kocho — Insect Hashira 🦋
Tengen Uzui — Sound Hashira 🎵
Mitsuri Kanroji — Love Hashira 💗
Muichiro Tokito — Mist Hashira 🌫️
Sanemi Shinazugawa — Wind Hashira 🌪️
Gyomei Himejima — Stone Hashira 🪨
Obanai Iguro — Serpent Hashira 🐍

The Hashira aren’t just powerful—they are essentially the Corps’ greatest line of defense against the strongest demons.

⸻

🌸 The Hidden Side of Society

One of the most interesting parts of the world is that humans and demons exist in the same society without most humans realizing it.

A demon could potentially live among humans, hide their identity, and appear completely normal.

Meanwhile, a Demon Slayer might be traveling through the same town, secretly searching for them.

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The world of Demon Slayer: set during the Taishō era (1912–1926). It looks like ordinary Japan on the surface—cities, villages, trains, schools, shops, and families—but hidden from ordinary people is a terrifying supernatural world ruled by demons.

🏯 The Human World

Most humans have no idea demons exist.

People live normal lives in villages and cities, working, traveling, going to festivals, and riding trains. But once night falls, traveling through isolated forests, mountains, or rural roads can become extremely dangerous.

Demons usually hunt after sunset because sunlight is deadly to them.

This creates a strange contrast:

Daytime: 🌸
Normal human life, markets, villages, families, travelers.

Nighttime: 🌙
Demons emerge, people disappear, and Demon Slayers secretly hunt their prey.

⸻

🩸 Demons

Demons are humans who have been transformed through Muzan Kibutsuji’s blood.

After becoming demons, they gain supernatural abilities such as:

• Incredible strength
• Extreme speed
• Regeneration
• Enhanced senses
• Immense durability
• Long lifespans
• Blood Demon Arts

Their abilities become more powerful depending on the individual.

However, demons have major weaknesses:

☀️ Sunlight — normally fatal.
⚔️ Nichirin swords — can kill them when used properly.
🔥 Wisteria — poisonous and dangerous to demons.

Most demons also need to consume humans to survive.

👑 Muzan Kibutsuji

At the center of the demon world is Muzan Kibutsuji, the first and most powerful demon.

He created most of the demons that exist and controls them through his blood.

Muzan’s ultimate obsession is overcoming his greatest weakness:

the sun.

Because of this, he searches for anything that could allow him to become completely immortal and immune to sunlight.

⸻

🌙 The Twelve Kizuki

Muzan’s strongest demons belong to an elite group called the Twelve Kizuki.

They are divided into:

Upper Ranks

The strongest demons.

Upper Rank One → Upper Rank Six

These demons are extraordinarily powerful and can survive against even elite Demon Slayers.

Lower Ranks

Also numbered from One to Six.

They are weaker than the Upper Ranks, although even a Lower Rank demon can be extremely dangerous to ordinary humans.

Muzan can replace members who disappoint him.

The Infinity Castle is the enormous supernatural fortress used by Muzan and the Upper Moons. It isn’t a normal building—it is a constantly shifting dimension controlled by Nakime.

🏯 What it looks like

• Endless rooms, halls, staircases, and platforms.
• Floors and walls can appear to stretch in impossible directions.
• Rooms can move, rotate, disappear, or connect to completely different areas.
• There doesn’t seem to be a normal entrance or exit.
• Its architecture resembles traditional Japanese buildings, but on an impossible scale.

🎵 Nakime’s control

Nakime sits inside the castle with her biwa.

Whenever she plays it, the castle responds.

She can essentially rearrange the entire environment around whoever is inside.

For example:

One biwa note 🎵 → a room moves.

Another note 🎵 → someone is transported somewhere else.

Another 🎵 → entire groups can become separated.

This makes the castle incredibly difficult to navigate without Nakime’s cooperation.

🩸 Muzan’s fortress

The Infinity Castle is where Muzan can gather the Upper Moons and other demons.

It’s particularly useful because Muzan can keep his strongest demons away from ordinary Demon Slayers.

The castle also allows him to communicate with and summon his demons whenever he wants.

⚔️ Why it’s so dangerous

Imagine fighting an Upper Moon while the battlefield itself keeps changing.

You could be standing on a floor one second…

Then suddenly:

The floor becomes a wall.
You fall—
—but instead of hitting the ground, you enter another room.
Then the room shifts again.
You don’t know where your opponent is.
You don’t know where the exit is.
And Nakime is watching everything.

🖤 The most interesting thing about it

The Infinity Castle isn’t just a place where the final battles happen.

It’s basically Nakime’s weapon.

She doesn’t need to chase someone.

She doesn’t need to overpower them.

As long as they’re inside her territory, she controls where they can go.

Muzan Kibutsuji is the first demon. He is essentially the origin of every demon created through his blood.

🖤 Appearance

• Age: Over 1,000 years old
• Height: Around 179 cm
• Hair: Black, sometimes appearing reddish under certain lighting
• Eyes: Deep red, with a frightening intensity
• Usually dresses in an elegant black suit, white shirt, tie, and hat.
• He can completely change his appearance and even disguise himself as different people.

🧠 Personality

Muzan is extremely self-centered, calculating, paranoid, and ruthless.

He doesn’t see demons as equals or companions. To him, they’re tools. Even the Upper Moons—despite their incredible strength—exist mainly because they are useful to him.

His greatest obsession is survival. He fears death and anything that could threaten his existence.

What makes him especially terrifying is that he doesn’t usually need to scream or act wildly. He can remain calm and polite while deciding someone’s death.

🩸 Abilities

Demon Blood

• His blood can transform humans into demons.

• The stronger the dose, the more dangerous the transformation can become.

• His blood also allows him to control and influence demons.
  Biokinesis
  Muzan can manipulate his own body almost freely:

• Create additional limbs.

• Transform his body.

• Extend blades and tentacles from his flesh.

• Regenerate from devastating injuries.

• Change his physical appearance.
  Immense Regeneration
  His regeneration is on another level compared with ordinary demons.
  Multiple Hearts & Brains
  His body contains multiple vital organs, making him extremely difficult to kill.
  Demon Control
  Muzan can communicate with demons and punish those who betray him. The curse connected to his blood can also kill demons who say his name.

👑 His greatest weakness

Despite being unbelievably powerful, Muzan is terrified of death.
His entire existence revolves around finding a way to become completely immune to the sun. That’s why the Blue Spider Lily

Kokushibo

Basic Information

• Human name: Michikatsu Tsugikuni
• Rank: Upper Rank One
• Age: Over 480 years as a demon
• Breathing Style: Moon Breathing
• Weapon: A demonic sword created from his own flesh
• Blood Demon Art: Moon-based attacks combined with his swordsmanship
• Affiliation: Twelve Kizuki

Appearance

Kokushibo is immediately recognizable because of his six eyes.

His long black hair, pale skin, traditional clothing, and enormous demonic sword give him an ancient samurai-like appearance. His eyes allow him to observe his opponents with extraordinary precision.

His sword itself is horrifying—it is made from his flesh and constantly changes as his demonic abilities develop.

Personality

Kokushibo is extremely calm, disciplined, serious, and prideful.

Unlike many demons, he doesn’t behave like a wild monster. He speaks formally and treats combat almost like a sacred discipline.

His greatest obsession is strength.

But underneath that obsession is something much more complicated: jealousy toward his younger twin brother, Yoriichi.

Kokushibo spent his entire human life comparing himself to someone he could never surpass.

Human Life

Kokushibo was originally Michikatsu Tsugikuni, the older twin brother of Yoriichi Tsugikuni.

Yoriichi was born with extraordinary natural talent and eventually became the greatest swordsman of his era.

Michikatsu desperately wanted to surpass him.

That jealousy gradually consumed him.

Even after becoming a demon, he continued pursuing greater strength because he couldn’t accept being inferior to Yoriichi.

Fighting Style — Moon Breathing 🌙

Kokushibo developed Moon Breathing, derived from Sun Breathing.

His sword techniques create enormous numbers of crescent-shaped attacks.

The terrifying part is that the crescents aren’t simply predictable projectiles. Their size, direction, and positioning make them extremely difficult to avoid.

Combined with his six eyes and supernatural physical abilities, his swordsmanship becomes overwhelming.

Blood Demon Art

Kokushibo’s Blood Demon Art works together with Moon Breathing.

He can generate countless crescent-shaped blades from his attacks.

His techniques therefore combine:

Swordsmanship + Blood Demon Art + Demonic regeneration

This makes his fighting style extremely difficult to counter.

Relationship With Muzan

Kokushibo is one of Muzan’s most valuable demons.

Muzan respects his strength and allows him considerably more independence than most demons.

Kokushibo, meanwhile, follows Muzan because becoming a demon allowed him to continue pursuing strength and escape the limitations of human life.

Biggest Tragedy

Kokushibo achieved almost everything he wanted.

He became immortal.

He became one of the strongest beings alive.

He surpassed almost every swordsman.

Yet he never escaped his jealousy of Yoriichi.

Doma

Basic Information

• Rank: Upper Rank Two
• Human age: 20 when transformed
• Weapon: Folding war fans
• Blood Demon Art: Cryokinesis / Ice
• Affiliation: Twelve Kizuki

Appearance

Doma has an unusually beautiful appearance.

He has:

• Long pale-blond hair
• Rainbow-colored eyes
• Extremely pale skin
• Elaborate clothing
• Two golden war fans

His appearance makes him look almost divine—which fits his personality perfectly.

Personality

Doma is one of the most disturbing demons because he is cheerful, friendly, and seemingly compassionate.

But his emotions are deeply abnormal.

He doesn’t genuinely experience emotions the way humans do.

He can smile while killing someone.

He can speak warmly while committing horrific acts.

He considers himself compassionate because he believes that consuming people frees them from suffering.

Human Life

Doma was born into a religious cult.

His unusual appearance caused his parents to treat him as something special.

People began worshipping him and asking him for advice.

Doma learned from childhood that people were emotionally dependent on him.

But he never truly understood their emotions.

Blood Demon Art — Ice ❄️

Doma’s Blood Demon Art allows him to create and manipulate supernatural ice.

His abilities include:

• Ice clones
• Frozen lotus flowers
• Ice clouds
• Giant ice structures
• Freezing attacks
• An enormous ice statue

His ice can be extremely dangerous because inhaling particles from it can damage the lungs.

Weapons

Doma uses two golden war fans.

Rather than relying only on physical strength, he combines his fans with his ice abilities to create wide-area attacks.

Relationship With Muzan

Doma respects Muzan but doesn’t seem emotionally attached to him.

His personality makes him difficult to read.

He can appear loyal while simultaneously remaining emotionally detached from almost everyone.

Relationship With Akaza

Akaza absolutely hates Doma.

Doma, however, finds Akaza amusing and enjoys provoking

Akaza

Basic Information

• Human name: Hakuji
• Rank: Upper Rank Three
• Human age: 18 when transformed
• Blood Demon Art: Destructive Death
• Fighting style: Martial arts
• Special ability: Compass Needle

Appearance

Akaza has:

• Pink hair
• Blue tattoo-like markings across his body
• Yellow eyes
• Muscular physique
• A powerful, athletic build

His appearance reflects his obsession with martial arts.

Personality

Akaza is aggressive, proud, competitive, and obsessed with strength.

But unlike Doma, Akaza has genuine emotions.

He respects strong opponents.

He hates weakness.

And he strongly dislikes people who don’t take fighting seriously.

Human Life — Hakuji

Hakuji had an extremely painful childhood.

His father was sick, and Hakuji stole medicine to help him.

Eventually, Hakuji’s father died.

Later, Hakuji was taken in by a martial arts master named Keizo.

There, he met Koyuki, Keizo’s daughter.

Koyuki became the most important person in his life.

For the first time, Hakuji had something resembling a family and a future.

Then tragedy destroyed everything.

Koyuki and Keizo were poisoned.

Hakuji lost the two people he loved most.

His grief and rage eventually led him to Muzan.

Blood Demon Art — Destructive Death

Akaza’s fighting style revolves around martial arts.

He creates shockwaves and devastating attacks using his fists and feet.

His techniques include:

• Air Type
• Compass Needle
• Annihilation Type
• Disorder
• Explosive Flurry

Compass Needle

This is one of Akaza’s most dangerous abilities.

He can sense an opponent’s fighting spirit and use it to determine their location and movements.

This makes escaping from him extremely difficult.

Relationship With Muzan

Akaza obeys Muzan but doesn’t appear emotionally devoted to him.

Muzan values Akaza because he is incredibly strong and consistently useful.

The Tragic Part

Akaza remembers almost nothing about his human life consciously.
But deep inside, Hakuji still exists.

Nakime

Basic Information

• Name: Nakime
• Rank: Upper Rank Four
• Former Upper Rank Four: Hantengu
• Weapon: Biwa
• Blood Demon Art: Infinity Castle manipulation
• Affiliation: Twelve Kizuki
• Role: Controller of the Infinity Castle

👁️ Appearance

Nakime has a very distinctive appearance:

• Long, dark hair covering much of her face
• Pale skin
• A single visible eye
• Traditional Japanese clothing
• A biwa, a Japanese string instrument

She rarely shows strong emotion and usually maintains a completely calm expression.

🧠 Personality

Nakime is quiet, serious, obedient, and extremely composed.

Unlike Doma or Gyokko, she doesn’t seek attention.

She mostly communicates through her biwa and short statements.

Her silence actually makes her more intimidating.

🎵 Blood Demon Art — Infinity Castle

This is what makes Nakime so important.

By playing her biwa, she can manipulate the Infinity Castle.

She can:

• Move rooms around.
• Change the castle’s layout.
• Separate people.
• Bring demons and humans to different locations.
• Create enormous distances between opponents.
• Control doors and pathways.
• Track people inside the castle.
• Make the castle itself function almost like a weapon.

Basically, the Infinity Castle is an extension of her ability.

👑 Her Relationship With Muzan

Nakime becomes extremely valuable to Muzan because her ability gives him control over the Infinity Castle.

She can instantly relocate him and the other demons, making the castle an almost perfect fortress.

Muzan trusts her with an enormous amount of responsibility.

⚔️ How She Became Upper Rank Four

After Hantengu was defeated, there was a vacancy in the Upper Ranks.

Muzan promoted Nakime to Upper Rank Four.

This is important because Nakime isn’t necessarily the strongest fighter among the Upper Moons.

Her value comes from her unique ability.

She can control the battlefield itself.

☠️ Why She’s Dangerous

Imagine fighting a demon who doesn’t need to attack you directly.

You’re chasing Muzan?

The room moves.

You’re trying to reach another Demon Slayer?

The path disappears.

You think you’ve found the exit?

You’re suddenly somewhere completely different.

That’s Nakime’s real strength.

She’s less of a traditional fighter and more of a battlefield controller.

🎶 Her Most Important Role

Nakime is basically the heart of the Infinity Castle.

While demons like Kokushibo and Akaza specialize in direct combat, Nakime controls the environment around everyone.

Hantengu

Personality

Hantengu is a coward.

He constantly claims that he’s innocent and that other people are responsible for his actions.

But his cowardice hides something much darker:

He refuses to accept responsibility for anything.

Blood Demon Art

His greatest ability is splitting himself into different emotional manifestations.

The major forms represent emotions such as:

• Sekido — Anger
• Karaku — Pleasure
• Aizetsu — Sorrow
• Urogi — Joy
• Zohakuten — Hatred

Each form has different abilities.

This makes fighting Hantengu incredibly complicated because defeating one body doesn’t necessarily defeat the actual demon.

Zohakuten

Zohakuten is the most powerful manifestation.

He can use powerful wooden dragon attacks and represents Hantengu’s hatred.

Human Personality

Even as a human, Hantengu constantly lied and denied responsibility.

Becoming a demon didn’t fundamentally change him.

It simply gave his worst traits supernatural power.

Gyokko

Personality

Gyokko is vain, arrogant, eccentric, and obsessed with his own artistic genius.

He sees himself as an artist.

Unfortunately, his idea of art is horrifying.

He considers mutilated bodies and grotesque creations to be beautiful.

Appearance

His body is extremely unusual.

Instead of having normal legs, his lower body resembles a fish-like creature emerging from a pot.

His appearance becomes even more monstrous when he enters his true form.

Blood Demon Art

Gyokko’s abilities revolve around pots and aquatic creatures.

He can:

• Teleport through pots
• Create fish-like creatures
• Trap people
• Attack with water
• Create strange monsters
• Manipulate his environment through his pots

True Form

After transforming further, Gyokko gains a much more powerful body.

His scales become extremely durable and his physical abilities increase dramatically.

Personality Toward Muzan

Gyokko desperately wants Muzan to appreciate his artistic creations.

He is essentially obsessed with receiving recognition.

Gyutaro and Daki

Unlike the other Upper Moons, Upper Rank Six is shared by two siblings.

Gyutaro

Gyutaro is:

• Extremely thin
• Covered in scars
• Possessive
• Bitter
• Jealous
• Extremely protective of Daki

His Blood Demon Art uses blood sickles.

His poisoned blood makes his attacks especially dangerous.

Daki

Daki appears beautiful and elegant because she was originally a highly successful oiran.

Her Blood Demon Art uses her obi sashes as weapons.

She can manipulate them like living weapons and store people inside them.

Their Relationship

Their relationship is the emotional core of Upper Rank Six.

Gyutaro genuinely loves Daki.

Daki, meanwhile, depends heavily on her brother.

They are cruel to almost everyone else, but toward each other their bond is extremely strong.

Human Life

They were born into extreme poverty in the Entertainment District.

Gyutaro grew up being mocked and mistreated because of his appearance.

Daki was born beautiful and eventually became valuable because of it.

Their lives eventually led to tragedy, and they became demons together.

Their Weakness

Because they share the same rank, both must be defeated.

Decapitating only one of them isn’t enough.

What Makes Them Different

The Upper Moons are terrifying individually.

But Gyutaro and Daki are terrifying because they function as one unit.

Their strongest weapon isn’t simply their Blood Demon Arts.

It’s their bond as siblings.